This is a note to let you know that I've just added the patch titled
perf: Fix fasync handling on inherited events
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
perf-fix-fasync-handling-on-inherited-events.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From fed66e2cdd4f127a43fd11b8d92a99bdd429528c Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <[email protected]>
Date: Thu, 11 Jun 2015 10:32:01 +0200
Subject: perf: Fix fasync handling on inherited events
From: Peter Zijlstra <[email protected]>
commit fed66e2cdd4f127a43fd11b8d92a99bdd429528c upstream.
Vince reported that the fasync signal stuff doesn't work proper for
inherited events. So fix that.
Installing fasync allocates memory and sets filp->f_flags |= FASYNC,
which upon the demise of the file descriptor ensures the allocation is
freed and state is updated.
Now for perf, we can have the events stick around for a while after the
original FD is dead because of references from child events. So we
cannot copy the fasync pointer around. We can however consistently use
the parent's fasync, as that will be updated.
Reported-and-Tested-by: Vince Weaver <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Arnaldo Carvalho deMelo <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/1434011521.1495.71.camel@twins
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
kernel/events/core.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4218,12 +4218,20 @@ static const struct file_operations perf
* to user-space before waking everybody up.
*/
+static inline struct fasync_struct **perf_event_fasync(struct perf_event
*event)
+{
+ /* only the parent has fasync state */
+ if (event->parent)
+ event = event->parent;
+ return &event->fasync;
+}
+
void perf_event_wakeup(struct perf_event *event)
{
ring_buffer_wakeup(event);
if (event->pending_kill) {
- kill_fasync(&event->fasync, SIGIO, event->pending_kill);
+ kill_fasync(perf_event_fasync(event), SIGIO,
event->pending_kill);
event->pending_kill = 0;
}
}
@@ -5432,7 +5440,7 @@ static int __perf_event_overflow(struct
else
perf_event_output(event, data, regs);
- if (event->fasync && event->pending_kill) {
+ if (*perf_event_fasync(event) && event->pending_kill) {
event->pending_wakeup = 1;
irq_work_queue(&event->pending);
}
Patches currently in stable-queue which might be from [email protected] are
queue-3.14/perf-fix-perf_event_ioc_period-migration-race.patch
queue-3.14/ipc-sem.c-update-correct-memory-barriers.patch
queue-3.14/perf-fix-fasync-handling-on-inherited-events.patch
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