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))
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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On Mon, Apr 15, 2019 at 08:04:33AM +0000, Ben Gainey wrote:
Hi Alex
I was just wondering if this was expected to make 5.1? (I could not see it in RC5)?
Yikes, I forgot about this again, didn't I ?
At least, they appear to still apply, so I've queued them. Not sure they'll still make this release, but at least they should not go missing _again_.
Thanks Peter :-)
On Mon, 2019-04-15 at 11:16 +0200, Peter Zijlstra wrote:
On Mon, Apr 15, 2019 at 08:04:33AM +0000, Ben Gainey wrote:
Hi Alex
I was just wondering if this was expected to make 5.1? (I could not see it in RC5)?
Yikes, I forgot about this again, didn't I ?
At least, they appear to still apply, so I've queued them. Not sure they'll still make this release, but at least they should not go missing _again_.
Commit-ID: 339bc4183596e1f68c2c98a03b87aa124107c317 Gitweb: https://git.kernel.org/tip/339bc4183596e1f68c2c98a03b87aa124107c317 Author: Alexander Shishkin alexander.shishkin@linux.intel.com AuthorDate: Fri, 29 Mar 2019 11:13:38 +0200 Committer: Ingo Molnar mingo@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.Gainey@arm.com Tested-by: Ben Gainey Ben.Gainey@arm.com Signed-off-by: Alexander Shishkin alexander.shishkin@linux.intel.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Cc: stable@vger.kernel.org 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 Fixes: 1627314fb54a33e ("perf: Suppress AUX/OVERWRITE records") Link: https://lkml.kernel.org/r/20190329091338.29999-1-alexander.shishkin@linux.in... Signed-off-by: Ingo Molnar mingo@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))
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