diff options
| author | Mike Galbraith <efault@gmx.de> | 2010-03-26 11:11:33 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-04-02 19:30:05 +0200 |
| commit | 8bb39f9aa068262732fe44b965d7a6eb5a5a7d67 (patch) | |
| tree | 820af25532c62179f518bda83ea27b6b21ee736b | |
| parent | 257ef9d21f1b008a6c7425544b36641c4325a922 (diff) | |
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@cn.fujitsu.com>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Tested-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1269598293.6174.8.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | 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 b0feb4795af..96aae13c796 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) |