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bpf: Add bpf_guard_preempt() convenience macro

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Add bpf_guard_preempt() macro that uses newly introduced
bpf_preempt_disable/enable() kfuncs to guard a critical section.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20240424225529.16782-1-alexei.starovoitov@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
This commit is contained in:
Alexei Starovoitov 2024-04-24 15:55:29 -07:00 committed by Martin KaFai Lau
parent 52578f7f53
commit 8ec3bf5c31
2 changed files with 24 additions and 5 deletions
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22
tools/testing/selftests/bpf/bpf_experimental.h
View File

@ -397,6 +397,28 @@ l_true: \
, [as]"i"((dst_as << 16) | src_as));
#endif
void bpf_preempt_disable(void) __weak __ksym;
void bpf_preempt_enable(void) __weak __ksym;
typedef struct {
} __bpf_preempt_t;
static inline __bpf_preempt_t __bpf_preempt_constructor(void)
{
__bpf_preempt_t ret = {};
bpf_preempt_disable();
return ret;
}
static inline void __bpf_preempt_destructor(__bpf_preempt_t *t)
{
bpf_preempt_enable();
}
#define bpf_guard_preempt() \
__bpf_preempt_t ___bpf_apply(preempt, __COUNTER__) \
__attribute__((__unused__, __cleanup__(__bpf_preempt_destructor))) = \
__bpf_preempt_constructor()
/* Description
* Assert that a conditional expression is true.
* Returns

7
tools/testing/selftests/bpf/progs/preempt_lock.c
View File

@ -3,9 +3,7 @@
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include "bpf_misc.h"
void bpf_preempt_disable(void) __ksym;
void bpf_preempt_enable(void) __ksym;
#include "bpf_experimental.h"
SEC("?tc")
__failure __msg("1 bpf_preempt_enable is missing")
@ -92,8 +90,7 @@ static __noinline void preempt_balance_subprog(void)
SEC("?tc")
__success int preempt_balance(struct __sk_buff *ctx)
{
bpf_preempt_disable();
bpf_preempt_enable();
bpf_guard_preempt();
return 0;
}