[tip:perf/core] perf: Fix 'perf sched record' deadlock
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From: tip-bot for Mike Galbraith on 2 Apr 2010 15:10 Commit-ID: 8bb39f9aa068262732fe44b965d7a6eb5a5a7d67 Gitweb: http://git.kernel.org/tip/8bb39f9aa068262732fe44b965d7a6eb5a5a7d67 Author: Mike Galbraith <efault(a)gmx.de> AuthorDate: Fri, 26 Mar 2010 11:11:33 +0100 Committer: Ingo Molnar <mingo(a)elte.hu> CommitDate: Fri, 2 Apr 2010 19:30:05 +0200 perf: Fix 'perf sched record' deadlock perf sched record can deadlock a box should the holder of handle->data->lock take an interrupt, and then attempt to acquire an rq lock held by a CPU trying to acquire the same lock. Disable interrupts. CPU0 CPU1 sched event with rq->lock held grab handle->data->lock spin on handle->data->lock interrupt try to grab rq->lock Reported-by: Li Zefan <lizf(a)cn.fujitsu.com> Signed-off-by: Mike Galbraith <efault(a)gmx.de> Tested-by: Li Zefan <lizf(a)cn.fujitsu.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra(a)chello.nl> Cc: Arnaldo Carvalho de Melo <acme(a)redhat.com> Cc: Frederic Weisbecker <fweisbec(a)gmail.com> LKML-Reference: <1269598293.6174.8.camel(a)marge.simson.net> Signed-off-by: Ingo Molnar <mingo(a)elte.hu> --- kernel/perf_event.c | 15 ++++++++++++--- 1 files changed, 12 insertions(+), 3 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index b0feb47..96aae13 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -3376,15 +3376,23 @@ static void perf_event_task_output(struct perf_event *event, struct perf_task_event *task_event) { struct perf_output_handle handle; - int size; struct task_struct *task = task_event->task; - int ret; + unsigned long flags; + int size, ret; + + /* + * If this CPU attempts to acquire an rq lock held by a CPU spinning + * in perf_output_lock() from interrupt context, it's game over. + */ + local_irq_save(flags); size = task_event->event_id.header.size; ret = perf_output_begin(&handle, event, size, 0, 0); - if (ret) + if (ret) { + local_irq_restore(flags); return; + } task_event->event_id.pid = perf_event_pid(event, task); task_event->event_id.ppid = perf_event_pid(event, current); @@ -3395,6 +3403,7 @@ static void perf_event_task_output(struct perf_event *event, perf_output_put(&handle, task_event->event_id); perf_output_end(&handle); + local_irq_restore(flags); } static int perf_event_task_match(struct perf_event *event) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |