[PATCH] oprofile: fix potential deadlock on oprofilefs_lock
nmi_cpu_setup() is called from hardirq context and acquires oprofilefs_lock.
alloc_event_buffer() and oprofilefs_ulong_from_user() acquire this lock
without disabling irqs, which could deadlock.
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/oprofile/event_buffer.c b/drivers/oprofile/event_buffer.c
index 00e937e..e7fbac5 100644
--- a/drivers/oprofile/event_buffer.c
+++ b/drivers/oprofile/event_buffer.c
@@ -70,11 +70,12 @@
int alloc_event_buffer(void)
{
int err = -ENOMEM;
+ unsigned long flags;
- spin_lock(&oprofilefs_lock);
+ spin_lock_irqsave(&oprofilefs_lock, flags);
buffer_size = fs_buffer_size;
buffer_watershed = fs_buffer_watershed;
- spin_unlock(&oprofilefs_lock);
+ spin_unlock_irqrestore(&oprofilefs_lock, flags);
if (buffer_watershed >= buffer_size)
return -EINVAL;