[PATCH] perf: Fix inheritance of aux_output groups

[PATCH] perf: Fix inheritance of aux_output groups

[Alexander Shishkin]

Commit

  b43762ef010 ("perf: Allow normal events to output AUX data")

forgets to configure aux_output relation in the inherited groups, which
results in child PEBS events forever failing to schedule.

Fix this by setting up the AUX output link in the inheritance path.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
---
 kernel/events/core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index f5bb2557d5f6..761995f21b30 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -12024,6 +12024,10 @@ static int inherit_group(struct perf_event *parent_event,
 					    child, leader, child_ctx);
 		if (IS_ERR(child_ctr))
 			return PTR_ERR(child_ctr);
+
+		if (sub->aux_event == parent_event &&
+		    !perf_get_aux_event(child_ctr, leader))
+			return -EINVAL;
 	}
 	return 0;
 }
-- 
2.23.0

Re: [PATCH] perf: Fix inheritance of aux_output groups

[Ingo Molnar]

* Alexander Shishkin <alexander.shishkin@linux.intel.com> wrote:

> Commit
> 
>   b43762ef010 ("perf: Allow normal events to output AUX data")

Missing 'a', the proper SHA1 is:

    ab43762ef010 ("perf: Allow normal events to output AUX data")

:-)

> forgets to configure aux_output relation in the inherited groups, which
> results in child PEBS events forever failing to schedule.
> 
> Fix this by setting up the AUX output link in the inheritance path.
> 
> Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> ---
>  kernel/events/core.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index f5bb2557d5f6..761995f21b30 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -12024,6 +12024,10 @@ static int inherit_group(struct perf_event *parent_event,
>  					    child, leader, child_ctx);
>  		if (IS_ERR(child_ctr))
>  			return PTR_ERR(child_ctr);
> +
> +		if (sub->aux_event == parent_event &&
> +		    !perf_get_aux_event(child_ctr, leader))
> +			return -EINVAL;

Could this explain weird 'perf top' failures I'm seeing on my desktop, 
which I was just about to debug and report?

Thanks,

	Ingo

[tip: perf/urgent] perf/core: Fix inheritance of aux_output groups

[tip-bot2 for Alexander Shishkin]

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     f733c6b508bcaa3441ba1eacf16efb9abd47489f
Gitweb:        https://git.kernel.org/tip/f733c6b508bcaa3441ba1eacf16efb9abd47489f
Author:        Alexander Shishkin <alexander.shishkin@linux.intel.com>
AuthorDate:    Fri, 04 Oct 2019 15:57:29 +03:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Mon, 07 Oct 2019 16:50:42 +02:00

perf/core: Fix inheritance of aux_output groups

Commit:

  ab43762ef010 ("perf: Allow normal events to output AUX data")

forgets to configure aux_output relation in the inherited groups, which
results in child PEBS events forever failing to schedule.

Fix this by setting up the AUX output link in the inheritance path.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191004125729.32397-1-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/events/core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 3f0cb82..f953dd1 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -11862,6 +11862,10 @@ static int inherit_group(struct perf_event *parent_event,
 					    child, leader, child_ctx);
 		if (IS_ERR(child_ctr))
 			return PTR_ERR(child_ctr);
+
+		if (sub->aux_event == parent_event &&
+		    !perf_get_aux_event(child_ctr, leader))
+			return -EINVAL;
 	}
 	return 0;
 }

Re: [PATCH] perf: Fix inheritance of aux_output groups

[Alexander Shishkin]

Ingo Molnar <mingo@kernel.org> writes:

> * Alexander Shishkin <alexander.shishkin@linux.intel.com> wrote:
>
>> Commit
>> 
>>   b43762ef010 ("perf: Allow normal events to output AUX data")
>
> Missing 'a', the proper SHA1 is:
>
>     ab43762ef010 ("perf: Allow normal events to output AUX data")
>
> :-)

Ouch, sorry about that.

> Could this explain weird 'perf top' failures I'm seeing on my desktop, 
> which I was just about to debug and report?

Unlikely; to trigger the above you'd have to manually enable the
aux_output thingy and that would require HW support to begin with.

Thanks,
--
Alex