fuse: request_end(): do once

When the connection is aborted it is possible that request_end() will be
called twice.  Use atomic test and set to do the actual ending only once.

test_and_set_bit() also provides the necessary barrier semantics so no
explicit smp_wmb() is necessary.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 7f37e55edc0e..cd242fc6a92b 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -384,14 +384,18 @@ __releases(fc->lock)
 {
         struct fuse_iqueue *fiq = &fc->iq;
         void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
+
+        if (test_and_set_bit(FR_FINISHED, &req->flags)) {
+                spin_unlock(&fc->lock);
+                return;
+        }
+
         req->end = NULL;
         spin_lock(&fiq->waitq.lock);
         list_del_init(&req->intr_entry);
         spin_unlock(&fiq->waitq.lock);
         WARN_ON(test_bit(FR_PENDING, &req->flags));
         WARN_ON(test_bit(FR_SENT, &req->flags));
-        smp_wmb();
-        set_bit(FR_FINISHED, &req->flags);
         if (test_bit(FR_BACKGROUND, &req->flags)) {
                 clear_bit(FR_BACKGROUND, &req->flags);
                 if (fc->num_background == fc->max_background)