linux/kernel/trace
Davidlohr Bueso 40d14da383 fgraph: Convert ret_stack tasklist scanning to rcu
It seems that alloc_retstack_tasklist() can also take a lockless
approach for scanning the tasklist, instead of using the big global
tasklist_lock. For this we also kill another deprecated and rcu-unsafe
tsk->thread_group user replacing it with for_each_process_thread(),
maintaining semantics.

Here tasklist_lock does not protect anything other than the list
against concurrent fork/exit. And considering that the whole thing
is capped by FTRACE_RETSTACK_ALLOC_SIZE (32), it should not be a
problem to have a pontentially stale, yet stable, list. The task cannot
go away either, so we don't risk racing with ftrace_graph_exit_task()
which clears the retstack.

The tsk->ret_stack management is not protected by tasklist_lock, being
serialized with the corresponding publish/subscribe barriers against
concurrent ftrace_push_return_trace(). In addition this plays nicer
with cachelines by avoiding two atomic ops in the uncontended case.

Link: https://lkml.kernel.org/r/20200907013326.9870-1-dave@stgolabs.net

Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-09-21 21:06:02 -04:00
..
blktrace.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
bpf_trace.c bpf: Remove inline from bpf_do_trace_printk 2020-08-06 16:53:17 -07:00
bpf_trace.h bpf: Use dedicated bpf_trace_printk event instead of trace_printk() 2020-07-13 16:55:49 -07:00
fgraph.c fgraph: Convert ret_stack tasklist scanning to rcu 2020-09-21 21:06:02 -04:00
ftrace_internal.h x86/ftrace: Have ftrace trampolines turn read-only at the end of system boot up 2020-05-12 18:24:34 -04:00
ftrace.c tracing: Delete repeated words in comments 2020-09-21 21:06:02 -04:00
Kconfig Tracing updates for 5.8: 2020-06-09 10:06:18 -07:00
kprobe_event_gen_test.c tracing: Add kprobe event command generation test module 2020-01-30 09:46:28 -05:00
Makefile Kbuild updates for v5.9 2020-08-09 14:10:26 -07:00
power-traces.c
preemptirq_delay_test.c tracing: Wait for preempt irq delay thread to execute 2020-05-11 17:00:34 -04:00
ring_buffer_benchmark.c sched,tracing: Convert to sched_set_fifo() 2020-07-29 11:43:53 +02:00
ring_buffer.c Tracing updates for 5.9 2020-08-07 18:29:15 -07:00
rpm-traces.c
synth_event_gen_test.c tracing: Have synthetic event test use raw_smp_processor_id() 2020-02-20 17:43:41 -05:00
trace_benchmark.c trace: Use pr_warn instead of pr_warning 2019-10-18 15:01:57 +02:00
trace_benchmark.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_boot.c tracing/boottime: Fix kprobe multiple events 2020-06-23 21:51:50 -04:00
trace_branch.c tracing: Make struct ring_buffer less ambiguous 2020-01-13 13:19:38 -05:00
trace_clock.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
trace_dynevent.c tracing: Delete repeated words in comments 2020-09-21 21:06:02 -04:00
trace_dynevent.h tracing: Remove check_arg() callbacks from dynevent args 2020-02-01 13:09:23 -05:00
trace_entries.h tracing: Make ftrace packed events have align of 1 2020-06-16 21:21:02 -04:00
trace_event_perf.c Merge branch 'perf/urgent' into perf/core, to pick up fixes 2019-10-28 12:38:26 +01:00
trace_events_filter_test.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_events_filter.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
trace_events_hist.c tracing: fix double free 2020-09-18 13:16:40 -04:00
trace_events_inject.c tracing: Initialize val to zero in parse_entry of inject code 2020-01-02 19:04:57 -05:00
trace_events_synth.c tracing: Delete repeated words in comments 2020-09-21 21:06:02 -04:00
trace_events_trigger.c tracing: Fix event trigger to accept redundant spaces 2020-06-23 21:51:40 -04:00
trace_events.c tracing: toplevel d_entry already initialized 2020-09-18 22:17:14 -04:00
trace_export.c tracing: Make ftrace packed events have align of 1 2020-06-16 21:21:02 -04:00
trace_functions_graph.c tracing: make tracing_init_dentry() returns an integer instead of a d_entry pointer 2020-09-18 22:17:14 -04:00
trace_functions.c trace: Fix typo in allocate_ftrace_ops()'s comment 2020-06-16 21:21:02 -04:00
trace_hwlat.c tracing: make tracing_init_dentry() returns an integer instead of a d_entry pointer 2020-09-18 22:17:14 -04:00
trace_irqsoff.c tracing: Rename trace_buffer to array_buffer 2020-01-13 13:19:38 -05:00
trace_kdb.c tracing: Rename trace_buffer to array_buffer 2020-01-13 13:19:38 -05:00
trace_kprobe_selftest.c selftest/ftrace: Move kprobe selftest function to separate compile unit 2018-07-30 18:41:04 -04:00
trace_kprobe_selftest.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_kprobe.c kprobes: Use module_name() macro 2020-09-21 21:06:02 -04:00
trace_mmiotrace.c tracing: Make struct ring_buffer less ambiguous 2020-01-13 13:19:38 -05:00
trace_nop.c
trace_output.c tracing: Make the space reserved for the pid wider 2020-09-18 12:42:11 -04:00
trace_output.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_preemptirq.c x86/entry: Rename trace_hardirqs_off_prepare() 2020-06-11 15:15:24 +02:00
trace_printk.c tracing: make tracing_init_dentry() returns an integer instead of a d_entry pointer 2020-09-18 22:17:14 -04:00
trace_probe_tmpl.h tracing/probe: Support user-space dereference 2019-05-25 23:04:42 -04:00
trace_probe.c tracing/probe: Fix memleak in fetch_op_data operations 2020-06-16 21:21:02 -04:00
trace_probe.h tracing/probe: Replace zero-length array with flexible-array 2020-06-15 23:08:32 -05:00
trace_sched_switch.c tracing: Fix sched switch start/stop refcount racy updates 2020-01-30 09:46:10 -05:00
trace_sched_wakeup.c tracing: Make struct ring_buffer less ambiguous 2020-01-13 13:19:38 -05:00
trace_selftest_dynamic.c
trace_selftest.c tracing: Rename trace_buffer to array_buffer 2020-01-13 13:19:38 -05:00
trace_seq.c tracing: Remove unused TRACE_SEQ_BUF_USED 2020-01-21 18:39:54 -05:00
trace_stack.c tracing: make tracing_init_dentry() returns an integer instead of a d_entry pointer 2020-09-18 22:17:14 -04:00
trace_stat.c tracing: make tracing_init_dentry() returns an integer instead of a d_entry pointer 2020-09-18 22:17:14 -04:00
trace_stat.h tracing: Use generic type for comparator function 2019-11-14 13:15:11 -05:00
trace_synth.h tracing: Move synthetic events to a separate file 2020-06-01 08:23:22 -04:00
trace_syscalls.c Tracing updates: 2020-02-06 07:12:11 +00:00
trace_uprobe.c tracing: make tracing_init_dentry() returns an integer instead of a d_entry pointer 2020-09-18 22:17:14 -04:00
trace.c tracing: remove a pointless assignment 2020-09-21 21:06:02 -04:00
trace.h tracing: make tracing_init_dentry() returns an integer instead of a d_entry pointer 2020-09-18 22:17:14 -04:00
tracing_map.c tracing: Delete repeated words in comments 2020-09-21 21:06:02 -04:00
tracing_map.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00