diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2019-05-17 13:52:33 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-06-22 08:16:16 +0200 |
| commit | a9a83106b163b50127d85c8a3f0684aa592e07be (patch) | |
| tree | da6bf4b10770a630c9a21ab970ba52520b1e88c0 /kernel/events | |
| parent | 2bc92a4f8be1427bf9bb9c6a5f9ac3377fd3b886 (diff) | |
perf/ring-buffer: Always use {READ,WRITE}_ONCE() for rb->user_page data
[ Upstream commit 4d839dd9e4356bbacf3eb0ab13a549b83b008c21 ]
We must use {READ,WRITE}_ONCE() on rb->user_page data such that
concurrent usage will see whole values. A few key sites were missing
this.
Suggested-by: Yabin Cui <yabinc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: acme@kernel.org
Cc: mark.rutland@arm.com
Cc: namhyung@kernel.org
Fixes: 7b732a750477 ("perf_counter: new output ABI - part 1")
Link: http://lkml.kernel.org/r/20190517115418.394192145@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel/events')
| -rw-r--r-- | kernel/events/ring_buffer.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index aef2af80a927..f3a69a4f0d57 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -101,7 +101,7 @@ again: * See perf_output_begin(). */ smp_wmb(); /* B, matches C */ - rb->user_page->data_head = head; + WRITE_ONCE(rb->user_page->data_head, head); /* * We must publish the head before decrementing the nest count, @@ -489,7 +489,7 @@ void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size) handle->aux_flags); } - rb->user_page->aux_head = rb->aux_head; + WRITE_ONCE(rb->user_page->aux_head, rb->aux_head); if (rb_need_aux_wakeup(rb)) wakeup = true; @@ -520,7 +520,7 @@ int perf_aux_output_skip(struct perf_output_handle *handle, unsigned long size) rb->aux_head += size; - rb->user_page->aux_head = rb->aux_head; + WRITE_ONCE(rb->user_page->aux_head, rb->aux_head); if (rb_need_aux_wakeup(rb)) { perf_output_wakeup(handle); handle->wakeup = rb->aux_wakeup + rb->aux_watermark; |