lkml.org 
[lkml]   [2017]   [Aug]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 02/10] perf: Fix leader for removed sibling event in perf_group_detach
    On Thu, Aug 24, 2017 at 06:27:29PM +0200, Jiri Olsa wrote:
    > Mark reported warning in x86_perf_event_update caused
    > by reading unscheduled leader of an event that was
    > already removed from the group.
    >
    > As he pointed out we don't properly reset event's leader
    > once it's been detached from the group and he posted the
    > attached fix.
    >
    > [1] https://marc.info/?l=linux-kernel&m=150238662928203&w=2
    >
    > Originally-From: Mark Rutland <mark.rutland@arm.com>
    > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
    > ---
    > kernel/events/core.c | 1 +
    > 1 file changed, 1 insertion(+)
    >
    > diff --git a/kernel/events/core.c b/kernel/events/core.c
    > index d704e23914bf..30e30e94ea32 100644
    > --- a/kernel/events/core.c
    > +++ b/kernel/events/core.c
    > @@ -1727,6 +1727,7 @@ static void perf_group_detach(struct perf_event *event)
    > if (event->group_leader != event) {
    > list_del_init(&event->group_entry);
    > event->group_leader->nr_siblings--;
    > + event->group_leader = event;
    > goto out;
    > }

    No, I think this breaks other things... but I again forgot what. The
    original issue he reported is fixed by patch:

    2bcb88eb04d3 ("perf/core: fix group {cpu,task} validation")

    Also by Mark.

    \
     
     \ /
      Last update: 2017-08-28 21:24    [W:4.052 / U:0.104 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site