Commit-ID: 339bc4183596e1f68c2c98a03b87aa124107c317
Gitweb: https://git.kernel.org/tip/339bc4183596e1f68c2c98a03b87aa124107c317
Author: Alexander Shishkin <alexander.shish...@linux.intel.com>
AuthorDate: Fri, 29 Mar 2019 11:13:38 +0200
Committer: Ingo Molnar <mi...@kernel.org>
CommitDate: Tue, 16 Apr 2019 12:13:57 +0200
perf/ring_buffer: Fix AUX record suppression
The following commit:
1627314fb54a33e ("perf: Suppress AUX/OVERWRITE records")
has an unintended side-effect of also suppressing all AUX records with no flags
and non-zero size, so all the regular records in the full trace mode.
This breaks some use cases for people.
Fix this by restoring "regular" AUX records.
Reported-by: Ben Gainey <ben.gai...@arm.com>
Tested-by: Ben Gainey <ben.gai...@arm.com>
Signed-off-by: Alexander Shishkin <alexander.shish...@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Cc: <sta...@vger.kernel.org>
Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
Cc: Jiri Olsa <jo...@redhat.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Stephane Eranian <eran...@google.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Vince Weaver <vincent.wea...@maine.edu>
Fixes: 1627314fb54a33e ("perf: Suppress AUX/OVERWRITE records")
Link:
https://lkml.kernel.org/r/20190329091338.29999-1-alexander.shish...@linux.intel.com
Signed-off-by: Ingo Molnar <mi...@kernel.org>
---
kernel/events/ring_buffer.c | 33 +++++++++++++++------------------
1 file changed, 15 insertions(+), 18 deletions(-)
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index 2545ac08cc77..5eedb49a65ea 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -455,24 +455,21 @@ void perf_aux_output_end(struct perf_output_handle
*handle, unsigned long size)
rb->aux_head += size;
}
- if (size || handle->aux_flags) {
- /*
- * Only send RECORD_AUX if we have something useful to
communicate
- *
- * Note: the OVERWRITE records by themselves are not considered
- * useful, as they don't communicate any *new* information,
- * aside from the short-lived offset, that becomes history at
- * the next event sched-in and therefore isn't useful.
- * The userspace that needs to copy out AUX data in overwrite
- * mode should know to use user_page::aux_head for the actual
- * offset. So, from now on we don't output AUX records that
- * have *only* OVERWRITE flag set.
- */
-
- if (handle->aux_flags & ~(u64)PERF_AUX_FLAG_OVERWRITE)
- perf_event_aux_event(handle->event, aux_head, size,
- handle->aux_flags);
- }
+ /*
+ * Only send RECORD_AUX if we have something useful to communicate
+ *
+ * Note: the OVERWRITE records by themselves are not considered
+ * useful, as they don't communicate any *new* information,
+ * aside from the short-lived offset, that becomes history at
+ * the next event sched-in and therefore isn't useful.
+ * The userspace that needs to copy out AUX data in overwrite
+ * mode should know to use user_page::aux_head for the actual
+ * offset. So, from now on we don't output AUX records that
+ * have *only* OVERWRITE flag set.
+ */
+ if (size || (handle->aux_flags & ~(u64)PERF_AUX_FLAG_OVERWRITE))
+ perf_event_aux_event(handle->event, aux_head, size,
+ handle->aux_flags);
rb->user_page->aux_head = rb->aux_head;
if (rb_need_aux_wakeup(rb))
