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authorSteven Rostedt (VMware) <rostedt@goodmis.org>2019-01-14 12:25:40 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2019-01-15 07:31:18 +1200
commit3719876809e745b9db5293d418600c194bbf5c23 (patch)
tree395e8ab29d48c025bae872b23830ad0c0fa47c03
parentc962cb323ec260652cff9331e7bf3d606292db88 (diff)
download96b-common-3719876809e745b9db5293d418600c194bbf5c23.tar.gz
sbitmap: Protect swap_lock from softirqs
The swap_lock used by sbitmap has a chain with locks taken from softirq, but the swap_lock is not protected from being preempted by softirqs. A chain exists of: sbq->ws[i].wait -> dispatch_wait_lock -> swap_lock Where the sbq->ws[i].wait lock can be taken from softirq context, which means all locks below it in the chain must also be protected from softirqs. Reported-by: Clark Williams <williams@redhat.com> Fixes: 58ab5e32e6fd ("sbitmap: silence bogus lockdep IRQ warning") Fixes: ea86ea2cdced ("sbitmap: amortize cost of clearing bits") Cc: Jens Axboe <axboe@kernel.dk> Cc: Ming Lei <ming.lei@redhat.com> Cc: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--lib/sbitmap.c12
1 files changed, 2 insertions, 10 deletions
diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index 65c2d06250a6..864354000e04 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -26,14 +26,9 @@
static inline bool sbitmap_deferred_clear(struct sbitmap *sb, int index)
{
unsigned long mask, val;
- unsigned long __maybe_unused flags;
bool ret = false;
- /* Silence bogus lockdep warning */
-#if defined(CONFIG_LOCKDEP)
- local_irq_save(flags);
-#endif
- spin_lock(&sb->map[index].swap_lock);
+ spin_lock_bh(&sb->map[index].swap_lock);
if (!sb->map[index].cleared)
goto out_unlock;
@@ -54,10 +49,7 @@ static inline bool sbitmap_deferred_clear(struct sbitmap *sb, int index)
ret = true;
out_unlock:
- spin_unlock(&sb->map[index].swap_lock);
-#if defined(CONFIG_LOCKDEP)
- local_irq_restore(flags);
-#endif
+ spin_unlock_bh(&sb->map[index].swap_lock);
return ret;
}