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authorLinus Torvalds <torvalds@linux-foundation.org>2009-12-12 14:46:33 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-12 14:46:33 -0800
commitf01eb3640308c005d31b29d0a8bc2b7acb4e3f75 (patch)
treea4e249cc4b5880b841487c889c32be8b5414fd11 /lib/kernel_lock.c
parent6698e34720660e18b45e2e3b115ee4584d0c3b5e (diff)
downloadlinux-2.6.34-ux500-f01eb3640308c005d31b29d0a8bc2b7acb4e3f75.tar.gz
[BKL] add 'might_sleep()' to the outermost lock taker
As shown by the previous patch (6698e3472: "tty: Fix BKL taken under a spinlock bug introduced in the BKL split") the BKL removal is prone to some subtle issues, where removing the BKL in one place may in fact make a previously nested BKL call the new outer call, and then prone to nasty deadlocks with other spinlocks. In general, we should never take the BKL while we're holding a spinlock, so let's just add a "might_sleep()" to it (even though the BKL doesn't technically sleep - at least not yet), and we'll get nice warnings the next time this kind of problem happens during BKL removal. Acked-and-Tested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/kernel_lock.c')
-rw-r--r--lib/kernel_lock.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/lib/kernel_lock.c b/lib/kernel_lock.c
index 4ebfa5a164d..5526b46aba9 100644
--- a/lib/kernel_lock.c
+++ b/lib/kernel_lock.c
@@ -122,8 +122,10 @@ void __lockfunc _lock_kernel(const char *func, const char *file, int line)
trace_lock_kernel(func, file, line);
- if (likely(!depth))
+ if (likely(!depth)) {
+ might_sleep();
__lock_kernel();
+ }
current->lock_depth = depth;
}