Re: [PATCH net 1/2] vhost: use mutex_lock_nested() in vhost_dev_lock_vqs()
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2018-01-23 15:58:14
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On Tue, Jan 23, 2018 at 05:27:25PM +0800, Jason Wang wrote:
We used to call mutex_lock() in vhost_dev_lock_vqs() which tries to
hold mutexes of all virtqueues. This may confuse lockdep to report a
possible deadlock because of trying to hold locks belong to same
class. Switch to use mutex_lock_nested() to avoid false positive.
Fixes: 6b1e6cc7855b0 ("vhost: new device IOTLB API")
Reported-by: syzbot+dbb7c1161485e61b0241@syzkaller.appspotmail.com
Signed-off-by: Jason Wang <jasowang@redhat.com>Acked-by: Michael S. Tsirkin <mst@redhat.com>
quoted hunk ↗ jump to hunk
--- drivers/vhost/vhost.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 33ac2b1..549771a 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c@@ -904,7 +904,7 @@ static void vhost_dev_lock_vqs(struct vhost_dev *d) { int i = 0; for (i = 0; i < d->nvqs; ++i) - mutex_lock(&d->vqs[i]->mutex); + mutex_lock_nested(&d->vqs[i]->mutex, i); } static void vhost_dev_unlock_vqs(struct vhost_dev *d)-- 2.7.4