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authorMike Galbraith <efault@gmx.de>2010-03-26 11:11:33 +0100
committerIngo Molnar <mingo@elte.hu>2010-04-02 19:30:05 +0200
commit8bb39f9aa068262732fe44b965d7a6eb5a5a7d67 (patch)
tree820af25532c62179f518bda83ea27b6b21ee736b /kernel
parent257ef9d21f1b008a6c7425544b36641c4325a922 (diff)
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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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/perf_event.c15
1 files changed, 12 insertions, 3 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index b0feb4795af3..96aae13c7960 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)