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>

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 7f37e55edc0e9f23425d37c9c1c4fae9a12860bb..cd242fc6a92bde7db31f2a49161c0c30de2d1aea 100644 (file)
--- 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)