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authorJeff Layton <jlayton@kernel.org>2019-03-25 08:15:14 -0400
committerJeff Layton <jlayton@kernel.org>2019-03-25 08:36:24 -0400
commit945ab8f6de94430c23a82f3cf2e3f6d6f2945ff7 (patch)
tree8f35ecd8e926416c684725ce93ee604164fd16d9 /fs
parent8c2ffd9174779014c3fe1f96d9dc3641d9175f00 (diff)
downloadlinux-stericsson-945ab8f6de94430c23a82f3cf2e3f6d6f2945ff7.tar.gz
locks: wake any locks blocked on request before deadlock check
Andreas reported that he was seeing the tdbtorture test fail in some cases with -EDEADLCK when it wasn't before. Some debugging showed that deadlock detection was sometimes discovering the caller's lock request itself in a dependency chain. While we remove the request from the blocked_lock_hash prior to reattempting to acquire it, any locks that are blocked on that request will still be present in the hash and will still have their fl_blocker pointer set to the current request. This causes posix_locks_deadlock to find a deadlock dependency chain when it shouldn't, as a lock request cannot block itself. We are going to end up waking all of those blocked locks anyway when we go to reinsert the request back into the blocked_lock_hash, so just do it prior to checking for deadlocks. This ensures that any lock blocked on the current request will no longer be part of any blocked request chain. URL: https://bugzilla.kernel.org/show_bug.cgi?id=202975 Fixes: 5946c4319ebb ("fs/locks: allow a lock request to block other requests.") Cc: stable@vger.kernel.org Reported-by: Andreas Schneider <asn@redhat.com> Signed-off-by: Neil Brown <neilb@suse.com> Signed-off-by: Jeff Layton <jlayton@kernel.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/locks.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/locks.c b/fs/locks.c
index eaa1cfaf73b0..71d0c6c2aac5 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1160,6 +1160,11 @@ static int posix_lock_inode(struct inode *inode, struct file_lock *request,
*/
error = -EDEADLK;
spin_lock(&blocked_lock_lock);
+ /*
+ * Ensure that we don't find any locks blocked on this
+ * request during deadlock detection.
+ */
+ __locks_wake_up_blocks(request);
if (likely(!posix_locks_deadlock(request, fl))) {
error = FILE_LOCK_DEFERRED;
__locks_insert_block(fl, request,