diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-12 14:46:33 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-12 14:46:33 -0800 |
| commit | f01eb3640308c005d31b29d0a8bc2b7acb4e3f75 (patch) | |
| tree | a4e249cc4b5880b841487c889c32be8b5414fd11 | |
| parent | 6698e34720660e18b45e2e3b115ee4584d0c3b5e (diff) | |
| download | linux-f01eb3640308c005d31b29d0a8bc2b7acb4e3f75.tar.bz2 | |
[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>
| -rw-r--r-- | lib/kernel_lock.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/lib/kernel_lock.c b/lib/kernel_lock.c index 4ebfa5a164d7..5526b46aba94 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; } |