Hi Alex
I was just wondering if this was expected to make 5.1? (I could not see it in RC5)?
Thanks Ben
On Fri, 2019-03-29 at 11:13 +0200, Alexander Shishkin wrote:
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.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com
Fixes: 1627314fb54a33e ("perf: Suppress AUX/OVERWRITE records") Reported-by: Ben Gainey Ben.Gainey@arm.com Tested-by: Ben Gainey Ben.Gainey@arm.com CC: stable@vger.kernel.org # v4.20+
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 678ccec60d8f..626256dc26c1 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))
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