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perf/core: Disable the event on a truncated AUX record
When the PMU driver reports a truncated AUX record, it effectively means that there is no more usable room in the event's AUX buffer (even though there may still be some room, so that perf_aux_output_begin() doesn't take action). At this point the consumer still has to be woken up and the event has to be disabled, otherwise the event will just keep spinning between perf_aux_output_begin() and perf_aux_output_end() until its context gets unscheduled. Again, for cpu-wide events this means never, so once in this condition, they will be forever losing data. Fix this by disabling the event and waking up the consumer in case of a truncated AUX record. Reported-by: Markus Metzger <markus.t.metzger@intel.com> Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Borislav Petkov <bp@alien8.de> 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: vince@deater.net Link: http://lkml.kernel.org/r/1462886313-13660-3-git-send-email-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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1 changed files with 9 additions and 1 deletions
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@ -405,6 +405,7 @@ void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size,
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bool truncated)
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bool truncated)
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{
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{
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struct ring_buffer *rb = handle->rb;
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struct ring_buffer *rb = handle->rb;
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bool wakeup = truncated;
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unsigned long aux_head;
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unsigned long aux_head;
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u64 flags = 0;
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u64 flags = 0;
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@ -433,9 +434,16 @@ void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size,
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aux_head = rb->user_page->aux_head = local_read(&rb->aux_head);
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aux_head = rb->user_page->aux_head = local_read(&rb->aux_head);
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if (aux_head - local_read(&rb->aux_wakeup) >= rb->aux_watermark) {
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if (aux_head - local_read(&rb->aux_wakeup) >= rb->aux_watermark) {
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perf_output_wakeup(handle);
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wakeup = true;
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local_add(rb->aux_watermark, &rb->aux_wakeup);
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local_add(rb->aux_watermark, &rb->aux_wakeup);
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}
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}
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if (wakeup) {
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if (truncated)
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handle->event->pending_disable = 1;
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perf_output_wakeup(handle);
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}
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handle->event = NULL;
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handle->event = NULL;
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local_set(&rb->aux_nest, 0);
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local_set(&rb->aux_nest, 0);
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