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linux/tools/lib/bpf/ringbuf.c

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libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
/*
* Ring buffer operations.
*
* Copyright (C) 2020 Facebook, Inc.
*/
libbpf: Add _GNU_SOURCE for reallocarray to ringbuf.c On systems with recent enough glibc, reallocarray compat won't kick in, so reallocarray() itself has to come from stdlib.h include. But _GNU_SOURCE is necessary to enable it. So add it. Fixes: bf99c936f947 ("libbpf: Add BPF ring buffer support") Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20200601202601.2139477-1-andriin@fb.com
2020-06-01 20:26:01 +00:00
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <linux/err.h>
#include <linux/bpf.h>
#include <asm/barrier.h>
#include <sys/mman.h>
#include <sys/epoll.h>
#include "libbpf.h"
#include "libbpf_internal.h"
#include "bpf.h"
struct ring {
ring_buffer_sample_fn sample_cb;
void *ctx;
void *data;
unsigned long *consumer_pos;
unsigned long *producer_pos;
unsigned long mask;
int map_fd;
};
struct ring_buffer {
struct epoll_event *events;
struct ring *rings;
size_t page_size;
int epoll_fd;
int ring_cnt;
};
static void ringbuf_unmap_ring(struct ring_buffer *rb, struct ring *r)
{
if (r->consumer_pos) {
munmap(r->consumer_pos, rb->page_size);
r->consumer_pos = NULL;
}
if (r->producer_pos) {
munmap(r->producer_pos, rb->page_size + 2 * (r->mask + 1));
r->producer_pos = NULL;
}
}
/* Add extra RINGBUF maps to this ring buffer manager */
int ring_buffer__add(struct ring_buffer *rb, int map_fd,
ring_buffer_sample_fn sample_cb, void *ctx)
{
struct bpf_map_info info;
__u32 len = sizeof(info);
struct epoll_event *e;
struct ring *r;
void *tmp;
int err;
memset(&info, 0, sizeof(info));
err = bpf_obj_get_info_by_fd(map_fd, &info, &len);
if (err) {
err = -errno;
pr_warn("ringbuf: failed to get map info for fd=%d: %d\n",
map_fd, err);
libbpf: Streamline error reporting for high-level APIs Implement changes to error reporting for high-level libbpf APIs to make them less surprising and less error-prone to users: - in all the cases when error happens, errno is set to an appropriate error value; - in libbpf 1.0 mode, all pointer-returning APIs return NULL on error and error code is communicated through errno; this applies both to APIs that already returned NULL before (so now they communicate more detailed error codes), as well as for many APIs that used ERR_PTR() macro and encoded error numbers as fake pointers. - in legacy (default) mode, those APIs that were returning ERR_PTR(err), continue doing so, but still set errno. With these changes, errno can be always used to extract actual error, regardless of legacy or libbpf 1.0 modes. This is utilized internally in libbpf in places where libbpf uses it's own high-level APIs. libbpf_get_error() is adapted to handle both cases completely transparently to end-users (and is used by libbpf consistently as well). More context, justification, and discussion can be found in "Libbpf: the road to v1.0" document ([0]). [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210525035935.1461796-5-andrii@kernel.org
2021-05-25 03:59:34 +00:00
return libbpf_err(err);
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
}
if (info.type != BPF_MAP_TYPE_RINGBUF) {
pr_warn("ringbuf: map fd=%d is not BPF_MAP_TYPE_RINGBUF\n",
map_fd);
libbpf: Streamline error reporting for high-level APIs Implement changes to error reporting for high-level libbpf APIs to make them less surprising and less error-prone to users: - in all the cases when error happens, errno is set to an appropriate error value; - in libbpf 1.0 mode, all pointer-returning APIs return NULL on error and error code is communicated through errno; this applies both to APIs that already returned NULL before (so now they communicate more detailed error codes), as well as for many APIs that used ERR_PTR() macro and encoded error numbers as fake pointers. - in legacy (default) mode, those APIs that were returning ERR_PTR(err), continue doing so, but still set errno. With these changes, errno can be always used to extract actual error, regardless of legacy or libbpf 1.0 modes. This is utilized internally in libbpf in places where libbpf uses it's own high-level APIs. libbpf_get_error() is adapted to handle both cases completely transparently to end-users (and is used by libbpf consistently as well). More context, justification, and discussion can be found in "Libbpf: the road to v1.0" document ([0]). [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210525035935.1461796-5-andrii@kernel.org
2021-05-25 03:59:34 +00:00
return libbpf_err(-EINVAL);
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
}
libbpf: Remove any use of reallocarray() in libbpf Re-implement glibc's reallocarray() for libbpf internal-only use. reallocarray(), unfortunately, is not available in all versions of glibc, so requires extra feature detection and using reallocarray() stub from <tools/libc_compat.h> and COMPAT_NEED_REALLOCARRAY. All this complicates build of libbpf unnecessarily and is just a maintenance burden. Instead, it's trivial to implement libbpf-specific internal version and use it throughout libbpf. Which is what this patch does, along with converting some realloc() uses that should really have been reallocarray() in the first place. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200819013607.3607269-2-andriin@fb.com
2020-08-19 01:36:04 +00:00
tmp = libbpf_reallocarray(rb->rings, rb->ring_cnt + 1, sizeof(*rb->rings));
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
if (!tmp)
libbpf: Streamline error reporting for high-level APIs Implement changes to error reporting for high-level libbpf APIs to make them less surprising and less error-prone to users: - in all the cases when error happens, errno is set to an appropriate error value; - in libbpf 1.0 mode, all pointer-returning APIs return NULL on error and error code is communicated through errno; this applies both to APIs that already returned NULL before (so now they communicate more detailed error codes), as well as for many APIs that used ERR_PTR() macro and encoded error numbers as fake pointers. - in legacy (default) mode, those APIs that were returning ERR_PTR(err), continue doing so, but still set errno. With these changes, errno can be always used to extract actual error, regardless of legacy or libbpf 1.0 modes. This is utilized internally in libbpf in places where libbpf uses it's own high-level APIs. libbpf_get_error() is adapted to handle both cases completely transparently to end-users (and is used by libbpf consistently as well). More context, justification, and discussion can be found in "Libbpf: the road to v1.0" document ([0]). [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210525035935.1461796-5-andrii@kernel.org
2021-05-25 03:59:34 +00:00
return libbpf_err(-ENOMEM);
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
rb->rings = tmp;
libbpf: Remove any use of reallocarray() in libbpf Re-implement glibc's reallocarray() for libbpf internal-only use. reallocarray(), unfortunately, is not available in all versions of glibc, so requires extra feature detection and using reallocarray() stub from <tools/libc_compat.h> and COMPAT_NEED_REALLOCARRAY. All this complicates build of libbpf unnecessarily and is just a maintenance burden. Instead, it's trivial to implement libbpf-specific internal version and use it throughout libbpf. Which is what this patch does, along with converting some realloc() uses that should really have been reallocarray() in the first place. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200819013607.3607269-2-andriin@fb.com
2020-08-19 01:36:04 +00:00
tmp = libbpf_reallocarray(rb->events, rb->ring_cnt + 1, sizeof(*rb->events));
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
if (!tmp)
libbpf: Streamline error reporting for high-level APIs Implement changes to error reporting for high-level libbpf APIs to make them less surprising and less error-prone to users: - in all the cases when error happens, errno is set to an appropriate error value; - in libbpf 1.0 mode, all pointer-returning APIs return NULL on error and error code is communicated through errno; this applies both to APIs that already returned NULL before (so now they communicate more detailed error codes), as well as for many APIs that used ERR_PTR() macro and encoded error numbers as fake pointers. - in legacy (default) mode, those APIs that were returning ERR_PTR(err), continue doing so, but still set errno. With these changes, errno can be always used to extract actual error, regardless of legacy or libbpf 1.0 modes. This is utilized internally in libbpf in places where libbpf uses it's own high-level APIs. libbpf_get_error() is adapted to handle both cases completely transparently to end-users (and is used by libbpf consistently as well). More context, justification, and discussion can be found in "Libbpf: the road to v1.0" document ([0]). [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210525035935.1461796-5-andrii@kernel.org
2021-05-25 03:59:34 +00:00
return libbpf_err(-ENOMEM);
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
rb->events = tmp;
r = &rb->rings[rb->ring_cnt];
memset(r, 0, sizeof(*r));
r->map_fd = map_fd;
r->sample_cb = sample_cb;
r->ctx = ctx;
r->mask = info.max_entries - 1;
/* Map writable consumer page */
tmp = mmap(NULL, rb->page_size, PROT_READ | PROT_WRITE, MAP_SHARED,
map_fd, 0);
if (tmp == MAP_FAILED) {
err = -errno;
pr_warn("ringbuf: failed to mmap consumer page for map fd=%d: %d\n",
map_fd, err);
libbpf: Streamline error reporting for high-level APIs Implement changes to error reporting for high-level libbpf APIs to make them less surprising and less error-prone to users: - in all the cases when error happens, errno is set to an appropriate error value; - in libbpf 1.0 mode, all pointer-returning APIs return NULL on error and error code is communicated through errno; this applies both to APIs that already returned NULL before (so now they communicate more detailed error codes), as well as for many APIs that used ERR_PTR() macro and encoded error numbers as fake pointers. - in legacy (default) mode, those APIs that were returning ERR_PTR(err), continue doing so, but still set errno. With these changes, errno can be always used to extract actual error, regardless of legacy or libbpf 1.0 modes. This is utilized internally in libbpf in places where libbpf uses it's own high-level APIs. libbpf_get_error() is adapted to handle both cases completely transparently to end-users (and is used by libbpf consistently as well). More context, justification, and discussion can be found in "Libbpf: the road to v1.0" document ([0]). [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210525035935.1461796-5-andrii@kernel.org
2021-05-25 03:59:34 +00:00
return libbpf_err(err);
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
}
r->consumer_pos = tmp;
/* Map read-only producer page and data pages. We map twice as big
* data size to allow simple reading of samples that wrap around the
* end of a ring buffer. See kernel implementation for details.
* */
tmp = mmap(NULL, rb->page_size + 2 * info.max_entries, PROT_READ,
MAP_SHARED, map_fd, rb->page_size);
if (tmp == MAP_FAILED) {
err = -errno;
ringbuf_unmap_ring(rb, r);
pr_warn("ringbuf: failed to mmap data pages for map fd=%d: %d\n",
map_fd, err);
libbpf: Streamline error reporting for high-level APIs Implement changes to error reporting for high-level libbpf APIs to make them less surprising and less error-prone to users: - in all the cases when error happens, errno is set to an appropriate error value; - in libbpf 1.0 mode, all pointer-returning APIs return NULL on error and error code is communicated through errno; this applies both to APIs that already returned NULL before (so now they communicate more detailed error codes), as well as for many APIs that used ERR_PTR() macro and encoded error numbers as fake pointers. - in legacy (default) mode, those APIs that were returning ERR_PTR(err), continue doing so, but still set errno. With these changes, errno can be always used to extract actual error, regardless of legacy or libbpf 1.0 modes. This is utilized internally in libbpf in places where libbpf uses it's own high-level APIs. libbpf_get_error() is adapted to handle both cases completely transparently to end-users (and is used by libbpf consistently as well). More context, justification, and discussion can be found in "Libbpf: the road to v1.0" document ([0]). [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210525035935.1461796-5-andrii@kernel.org
2021-05-25 03:59:34 +00:00
return libbpf_err(err);
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
}
r->producer_pos = tmp;
r->data = tmp + rb->page_size;
e = &rb->events[rb->ring_cnt];
memset(e, 0, sizeof(*e));
e->events = EPOLLIN;
e->data.fd = rb->ring_cnt;
if (epoll_ctl(rb->epoll_fd, EPOLL_CTL_ADD, map_fd, e) < 0) {
err = -errno;
ringbuf_unmap_ring(rb, r);
pr_warn("ringbuf: failed to epoll add map fd=%d: %d\n",
map_fd, err);
libbpf: Streamline error reporting for high-level APIs Implement changes to error reporting for high-level libbpf APIs to make them less surprising and less error-prone to users: - in all the cases when error happens, errno is set to an appropriate error value; - in libbpf 1.0 mode, all pointer-returning APIs return NULL on error and error code is communicated through errno; this applies both to APIs that already returned NULL before (so now they communicate more detailed error codes), as well as for many APIs that used ERR_PTR() macro and encoded error numbers as fake pointers. - in legacy (default) mode, those APIs that were returning ERR_PTR(err), continue doing so, but still set errno. With these changes, errno can be always used to extract actual error, regardless of legacy or libbpf 1.0 modes. This is utilized internally in libbpf in places where libbpf uses it's own high-level APIs. libbpf_get_error() is adapted to handle both cases completely transparently to end-users (and is used by libbpf consistently as well). More context, justification, and discussion can be found in "Libbpf: the road to v1.0" document ([0]). [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210525035935.1461796-5-andrii@kernel.org
2021-05-25 03:59:34 +00:00
return libbpf_err(err);
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
}
rb->ring_cnt++;
return 0;
}
void ring_buffer__free(struct ring_buffer *rb)
{
int i;
if (!rb)
return;
for (i = 0; i < rb->ring_cnt; ++i)
ringbuf_unmap_ring(rb, &rb->rings[i]);
if (rb->epoll_fd >= 0)
close(rb->epoll_fd);
free(rb->events);
free(rb->rings);
free(rb);
}
struct ring_buffer *
ring_buffer__new(int map_fd, ring_buffer_sample_fn sample_cb, void *ctx,
const struct ring_buffer_opts *opts)
{
struct ring_buffer *rb;
int err;
if (!OPTS_VALID(opts, ring_buffer_opts))
libbpf: Streamline error reporting for high-level APIs Implement changes to error reporting for high-level libbpf APIs to make them less surprising and less error-prone to users: - in all the cases when error happens, errno is set to an appropriate error value; - in libbpf 1.0 mode, all pointer-returning APIs return NULL on error and error code is communicated through errno; this applies both to APIs that already returned NULL before (so now they communicate more detailed error codes), as well as for many APIs that used ERR_PTR() macro and encoded error numbers as fake pointers. - in legacy (default) mode, those APIs that were returning ERR_PTR(err), continue doing so, but still set errno. With these changes, errno can be always used to extract actual error, regardless of legacy or libbpf 1.0 modes. This is utilized internally in libbpf in places where libbpf uses it's own high-level APIs. libbpf_get_error() is adapted to handle both cases completely transparently to end-users (and is used by libbpf consistently as well). More context, justification, and discussion can be found in "Libbpf: the road to v1.0" document ([0]). [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210525035935.1461796-5-andrii@kernel.org
2021-05-25 03:59:34 +00:00
return errno = EINVAL, NULL;
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
rb = calloc(1, sizeof(*rb));
if (!rb)
libbpf: Streamline error reporting for high-level APIs Implement changes to error reporting for high-level libbpf APIs to make them less surprising and less error-prone to users: - in all the cases when error happens, errno is set to an appropriate error value; - in libbpf 1.0 mode, all pointer-returning APIs return NULL on error and error code is communicated through errno; this applies both to APIs that already returned NULL before (so now they communicate more detailed error codes), as well as for many APIs that used ERR_PTR() macro and encoded error numbers as fake pointers. - in legacy (default) mode, those APIs that were returning ERR_PTR(err), continue doing so, but still set errno. With these changes, errno can be always used to extract actual error, regardless of legacy or libbpf 1.0 modes. This is utilized internally in libbpf in places where libbpf uses it's own high-level APIs. libbpf_get_error() is adapted to handle both cases completely transparently to end-users (and is used by libbpf consistently as well). More context, justification, and discussion can be found in "Libbpf: the road to v1.0" document ([0]). [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210525035935.1461796-5-andrii@kernel.org
2021-05-25 03:59:34 +00:00
return errno = ENOMEM, NULL;
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
rb->page_size = getpagesize();
rb->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
if (rb->epoll_fd < 0) {
err = -errno;
pr_warn("ringbuf: failed to create epoll instance: %d\n", err);
goto err_out;
}
err = ring_buffer__add(rb, map_fd, sample_cb, ctx);
if (err)
goto err_out;
return rb;
err_out:
ring_buffer__free(rb);
libbpf: Streamline error reporting for high-level APIs Implement changes to error reporting for high-level libbpf APIs to make them less surprising and less error-prone to users: - in all the cases when error happens, errno is set to an appropriate error value; - in libbpf 1.0 mode, all pointer-returning APIs return NULL on error and error code is communicated through errno; this applies both to APIs that already returned NULL before (so now they communicate more detailed error codes), as well as for many APIs that used ERR_PTR() macro and encoded error numbers as fake pointers. - in legacy (default) mode, those APIs that were returning ERR_PTR(err), continue doing so, but still set errno. With these changes, errno can be always used to extract actual error, regardless of legacy or libbpf 1.0 modes. This is utilized internally in libbpf in places where libbpf uses it's own high-level APIs. libbpf_get_error() is adapted to handle both cases completely transparently to end-users (and is used by libbpf consistently as well). More context, justification, and discussion can be found in "Libbpf: the road to v1.0" document ([0]). [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210525035935.1461796-5-andrii@kernel.org
2021-05-25 03:59:34 +00:00
return errno = -err, NULL;
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
}
static inline int roundup_len(__u32 len)
{
/* clear out top 2 bits (discard and busy, if set) */
len <<= 2;
len >>= 2;
/* add length prefix */
len += BPF_RINGBUF_HDR_SZ;
/* round up to 8 byte alignment */
return (len + 7) / 8 * 8;
}
libbpf: Fix signed overflow in ringbuf_process_ring One of our benchmarks running in (Google-internal) CI pushes data through the ringbuf faster htan than userspace is able to consume it. In this case it seems we're actually able to get >INT_MAX entries in a single ring_buffer__consume() call. ASAN detected that cnt overflows in this case. Fix by using 64-bit counter internally and then capping the result to INT_MAX before converting to the int return type. Do the same for the ring_buffer__poll(). Fixes: bf99c936f947 (libbpf: Add BPF ring buffer support) Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210429130510.1621665-1-jackmanb@google.com
2021-04-29 13:05:10 +00:00
static int64_t ringbuf_process_ring(struct ring* r)
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
{
libbpf: Fix signed overflow in ringbuf_process_ring One of our benchmarks running in (Google-internal) CI pushes data through the ringbuf faster htan than userspace is able to consume it. In this case it seems we're actually able to get >INT_MAX entries in a single ring_buffer__consume() call. ASAN detected that cnt overflows in this case. Fix by using 64-bit counter internally and then capping the result to INT_MAX before converting to the int return type. Do the same for the ring_buffer__poll(). Fixes: bf99c936f947 (libbpf: Add BPF ring buffer support) Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210429130510.1621665-1-jackmanb@google.com
2021-04-29 13:05:10 +00:00
int *len_ptr, len, err;
/* 64-bit to avoid overflow in case of extreme application behavior */
int64_t cnt = 0;
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
unsigned long cons_pos, prod_pos;
bool got_new_data;
void *sample;
cons_pos = smp_load_acquire(r->consumer_pos);
do {
got_new_data = false;
prod_pos = smp_load_acquire(r->producer_pos);
while (cons_pos < prod_pos) {
len_ptr = r->data + (cons_pos & r->mask);
len = smp_load_acquire(len_ptr);
/* sample not committed yet, bail out for now */
if (len & BPF_RINGBUF_BUSY_BIT)
goto done;
got_new_data = true;
cons_pos += roundup_len(len);
if ((len & BPF_RINGBUF_DISCARD_BIT) == 0) {
sample = (void *)len_ptr + BPF_RINGBUF_HDR_SZ;
err = r->sample_cb(r->ctx, sample, len);
libbpf: Fix bail out from 'ringbuf_process_ring()' on error The current code bails out with negative and positive returns. If the callback returns a positive return code, 'ring_buffer__consume()' and 'ring_buffer__poll()' will return a spurious number of records consumed, but mostly important will continue the processing loop. This patch makes positive returns from the callback a no-op. Fixes: bf99c936f947 ("libbpf: Add BPF ring buffer support") Signed-off-by: Pedro Tammela <pctammela@mojatatu.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210325150115.138750-1-pctammela@mojatatu.com
2021-03-25 15:01:15 +00:00
if (err < 0) {
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
/* update consumer pos and bail out */
smp_store_release(r->consumer_pos,
cons_pos);
return err;
}
cnt++;
}
smp_store_release(r->consumer_pos, cons_pos);
}
} while (got_new_data);
done:
return cnt;
}
/* Consume available ring buffer(s) data without event polling.
libbpf: Fix signed overflow in ringbuf_process_ring One of our benchmarks running in (Google-internal) CI pushes data through the ringbuf faster htan than userspace is able to consume it. In this case it seems we're actually able to get >INT_MAX entries in a single ring_buffer__consume() call. ASAN detected that cnt overflows in this case. Fix by using 64-bit counter internally and then capping the result to INT_MAX before converting to the int return type. Do the same for the ring_buffer__poll(). Fixes: bf99c936f947 (libbpf: Add BPF ring buffer support) Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210429130510.1621665-1-jackmanb@google.com
2021-04-29 13:05:10 +00:00
* Returns number of records consumed across all registered ring buffers (or
* INT_MAX, whichever is less), or negative number if any of the callbacks
* return error.
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
*/
int ring_buffer__consume(struct ring_buffer *rb)
{
libbpf: Fix signed overflow in ringbuf_process_ring One of our benchmarks running in (Google-internal) CI pushes data through the ringbuf faster htan than userspace is able to consume it. In this case it seems we're actually able to get >INT_MAX entries in a single ring_buffer__consume() call. ASAN detected that cnt overflows in this case. Fix by using 64-bit counter internally and then capping the result to INT_MAX before converting to the int return type. Do the same for the ring_buffer__poll(). Fixes: bf99c936f947 (libbpf: Add BPF ring buffer support) Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210429130510.1621665-1-jackmanb@google.com
2021-04-29 13:05:10 +00:00
int64_t err, res = 0;
int i;
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
for (i = 0; i < rb->ring_cnt; i++) {
struct ring *ring = &rb->rings[i];
err = ringbuf_process_ring(ring);
if (err < 0)
libbpf: Streamline error reporting for high-level APIs Implement changes to error reporting for high-level libbpf APIs to make them less surprising and less error-prone to users: - in all the cases when error happens, errno is set to an appropriate error value; - in libbpf 1.0 mode, all pointer-returning APIs return NULL on error and error code is communicated through errno; this applies both to APIs that already returned NULL before (so now they communicate more detailed error codes), as well as for many APIs that used ERR_PTR() macro and encoded error numbers as fake pointers. - in legacy (default) mode, those APIs that were returning ERR_PTR(err), continue doing so, but still set errno. With these changes, errno can be always used to extract actual error, regardless of legacy or libbpf 1.0 modes. This is utilized internally in libbpf in places where libbpf uses it's own high-level APIs. libbpf_get_error() is adapted to handle both cases completely transparently to end-users (and is used by libbpf consistently as well). More context, justification, and discussion can be found in "Libbpf: the road to v1.0" document ([0]). [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210525035935.1461796-5-andrii@kernel.org
2021-05-25 03:59:34 +00:00
return libbpf_err(err);
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
res += err;
}
libbpf: Fix signed overflow in ringbuf_process_ring One of our benchmarks running in (Google-internal) CI pushes data through the ringbuf faster htan than userspace is able to consume it. In this case it seems we're actually able to get >INT_MAX entries in a single ring_buffer__consume() call. ASAN detected that cnt overflows in this case. Fix by using 64-bit counter internally and then capping the result to INT_MAX before converting to the int return type. Do the same for the ring_buffer__poll(). Fixes: bf99c936f947 (libbpf: Add BPF ring buffer support) Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210429130510.1621665-1-jackmanb@google.com
2021-04-29 13:05:10 +00:00
if (res > INT_MAX)
return INT_MAX;
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
return res;
}
/* Poll for available data and consume records, if any are available.
libbpf: Fix signed overflow in ringbuf_process_ring One of our benchmarks running in (Google-internal) CI pushes data through the ringbuf faster htan than userspace is able to consume it. In this case it seems we're actually able to get >INT_MAX entries in a single ring_buffer__consume() call. ASAN detected that cnt overflows in this case. Fix by using 64-bit counter internally and then capping the result to INT_MAX before converting to the int return type. Do the same for the ring_buffer__poll(). Fixes: bf99c936f947 (libbpf: Add BPF ring buffer support) Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210429130510.1621665-1-jackmanb@google.com
2021-04-29 13:05:10 +00:00
* Returns number of records consumed (or INT_MAX, whichever is less), or
* negative number, if any of the registered callbacks returned error.
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
*/
int ring_buffer__poll(struct ring_buffer *rb, int timeout_ms)
{
libbpf: Fix signed overflow in ringbuf_process_ring One of our benchmarks running in (Google-internal) CI pushes data through the ringbuf faster htan than userspace is able to consume it. In this case it seems we're actually able to get >INT_MAX entries in a single ring_buffer__consume() call. ASAN detected that cnt overflows in this case. Fix by using 64-bit counter internally and then capping the result to INT_MAX before converting to the int return type. Do the same for the ring_buffer__poll(). Fixes: bf99c936f947 (libbpf: Add BPF ring buffer support) Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210429130510.1621665-1-jackmanb@google.com
2021-04-29 13:05:10 +00:00
int i, cnt;
int64_t err, res = 0;
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
cnt = epoll_wait(rb->epoll_fd, rb->events, rb->ring_cnt, timeout_ms);
libbpf: Fix signed overflow in ringbuf_process_ring One of our benchmarks running in (Google-internal) CI pushes data through the ringbuf faster htan than userspace is able to consume it. In this case it seems we're actually able to get >INT_MAX entries in a single ring_buffer__consume() call. ASAN detected that cnt overflows in this case. Fix by using 64-bit counter internally and then capping the result to INT_MAX before converting to the int return type. Do the same for the ring_buffer__poll(). Fixes: bf99c936f947 (libbpf: Add BPF ring buffer support) Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210429130510.1621665-1-jackmanb@google.com
2021-04-29 13:05:10 +00:00
if (cnt < 0)
libbpf: Streamline error reporting for high-level APIs Implement changes to error reporting for high-level libbpf APIs to make them less surprising and less error-prone to users: - in all the cases when error happens, errno is set to an appropriate error value; - in libbpf 1.0 mode, all pointer-returning APIs return NULL on error and error code is communicated through errno; this applies both to APIs that already returned NULL before (so now they communicate more detailed error codes), as well as for many APIs that used ERR_PTR() macro and encoded error numbers as fake pointers. - in legacy (default) mode, those APIs that were returning ERR_PTR(err), continue doing so, but still set errno. With these changes, errno can be always used to extract actual error, regardless of legacy or libbpf 1.0 modes. This is utilized internally in libbpf in places where libbpf uses it's own high-level APIs. libbpf_get_error() is adapted to handle both cases completely transparently to end-users (and is used by libbpf consistently as well). More context, justification, and discussion can be found in "Libbpf: the road to v1.0" document ([0]). [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210525035935.1461796-5-andrii@kernel.org
2021-05-25 03:59:34 +00:00
return libbpf_err(-errno);
libbpf: Fix signed overflow in ringbuf_process_ring One of our benchmarks running in (Google-internal) CI pushes data through the ringbuf faster htan than userspace is able to consume it. In this case it seems we're actually able to get >INT_MAX entries in a single ring_buffer__consume() call. ASAN detected that cnt overflows in this case. Fix by using 64-bit counter internally and then capping the result to INT_MAX before converting to the int return type. Do the same for the ring_buffer__poll(). Fixes: bf99c936f947 (libbpf: Add BPF ring buffer support) Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210429130510.1621665-1-jackmanb@google.com
2021-04-29 13:05:10 +00:00
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
for (i = 0; i < cnt; i++) {
__u32 ring_id = rb->events[i].data.fd;
struct ring *ring = &rb->rings[ring_id];
err = ringbuf_process_ring(ring);
if (err < 0)
libbpf: Streamline error reporting for high-level APIs Implement changes to error reporting for high-level libbpf APIs to make them less surprising and less error-prone to users: - in all the cases when error happens, errno is set to an appropriate error value; - in libbpf 1.0 mode, all pointer-returning APIs return NULL on error and error code is communicated through errno; this applies both to APIs that already returned NULL before (so now they communicate more detailed error codes), as well as for many APIs that used ERR_PTR() macro and encoded error numbers as fake pointers. - in legacy (default) mode, those APIs that were returning ERR_PTR(err), continue doing so, but still set errno. With these changes, errno can be always used to extract actual error, regardless of legacy or libbpf 1.0 modes. This is utilized internally in libbpf in places where libbpf uses it's own high-level APIs. libbpf_get_error() is adapted to handle both cases completely transparently to end-users (and is used by libbpf consistently as well). More context, justification, and discussion can be found in "Libbpf: the road to v1.0" document ([0]). [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210525035935.1461796-5-andrii@kernel.org
2021-05-25 03:59:34 +00:00
return libbpf_err(err);
libbpf: Fix ring_buffer__poll() to return number of consumed samples Fix ring_buffer__poll() to return the number of non-discarded records consumed, just like its documentation states. It's also consistent with ring_buffer__consume() return. Fix up selftests with wrong expected results. Fixes: bf99c936f947 ("libbpf: Add BPF ring buffer support") Fixes: cb1c9ddd5525 ("selftests/bpf: Add BPF ringbuf selftests") Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20201130223336.904192-1-andrii@kernel.org
2020-11-30 22:33:35 +00:00
res += err;
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
}
libbpf: Fix signed overflow in ringbuf_process_ring One of our benchmarks running in (Google-internal) CI pushes data through the ringbuf faster htan than userspace is able to consume it. In this case it seems we're actually able to get >INT_MAX entries in a single ring_buffer__consume() call. ASAN detected that cnt overflows in this case. Fix by using 64-bit counter internally and then capping the result to INT_MAX before converting to the int return type. Do the same for the ring_buffer__poll(). Fixes: bf99c936f947 (libbpf: Add BPF ring buffer support) Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210429130510.1621665-1-jackmanb@google.com
2021-04-29 13:05:10 +00:00
if (res > INT_MAX)
return INT_MAX;
return res;
libbpf: Add BPF ring buffer support Declaring and instantiating BPF ring buffer doesn't require any changes to libbpf, as it's just another type of maps. So using existing BTF-defined maps syntax with __uint(type, BPF_MAP_TYPE_RINGBUF) and __uint(max_elements, <size-of-ring-buf>) is all that's necessary to create and use BPF ring buffer. This patch adds BPF ring buffer consumer to libbpf. It is very similar to perf_buffer implementation in terms of API, but also attempts to fix some minor problems and inconveniences with existing perf_buffer API. ring_buffer support both single ring buffer use case (with just using ring_buffer__new()), as well as allows to add more ring buffers, each with its own callback and context. This allows to efficiently poll and consume multiple, potentially completely independent, ring buffers, using single epoll instance. The latter is actually a problem in practice for applications that are using multiple sets of perf buffers. They have to create multiple instances for struct perf_buffer and poll them independently or in a loop, each approach having its own problems (e.g., inability to use a common poll timeout). struct ring_buffer eliminates this problem by aggregating many independent ring buffer instances under the single "ring buffer manager". Second, perf_buffer's callback can't return error, so applications that need to stop polling due to error in data or data signalling the end, have to use extra mechanisms to signal that polling has to stop. ring_buffer's callback can return error, which will be passed through back to user code and can be acted upon appropariately. Two APIs allow to consume ring buffer data: - ring_buffer__poll(), which will wait for data availability notification and will consume data only from reported ring buffer(s); this API allows to efficiently use resources by reading data only when it becomes available; - ring_buffer__consume(), will attempt to read new records regardless of data availablity notification sub-system. This API is useful for cases when lowest latency is required, in expense of burning CPU resources. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-3-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 07:54:21 +00:00
}
libbpf: Expose libbpf ring_buffer epoll_fd This provides a convenient perf ringbuf -> libbpf ringbuf migration path for users of external polling systems. It is analogous to perf_buffer__epoll_fd. Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20201214113812.305274-1-jackmanb@google.com
2020-12-14 11:38:12 +00:00
/* Get an fd that can be used to sleep until data is available in the ring(s) */
int ring_buffer__epoll_fd(const struct ring_buffer *rb)
{
return rb->epoll_fd;
}
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