From: NeilBrown Date: Fri, 4 Mar 2016 06:20:13 +0000 (+1100) Subject: sunrpc/cache: drop reference when sunrpc_cache_pipe_upcall() detects a race X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=a6ab1e8126d205238defbb55d23661a3a5c6a0d8;p=linux-beck.git sunrpc/cache: drop reference when sunrpc_cache_pipe_upcall() detects a race sunrpc_cache_pipe_upcall() can detect a race if CACHE_PENDING is no longer set. In this case it aborts the queuing of the upcall. However it has already taken a new counted reference on "h" and doesn't "put" it, even though it frees the data structure holding the reference. So let's delay the "cache_get" until we know we need it. Fixes: f9e1aedc6c79 ("sunrpc/cache: remove races with queuing an upcall.") Signed-off-by: NeilBrown Signed-off-by: J. Bruce Fields --- diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c index 273bc3a35425..008c25d1b9f9 100644 --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -1182,14 +1182,14 @@ int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h) } crq->q.reader = 0; - crq->item = cache_get(h); crq->buf = buf; crq->len = 0; crq->readers = 0; spin_lock(&queue_lock); - if (test_bit(CACHE_PENDING, &h->flags)) + if (test_bit(CACHE_PENDING, &h->flags)) { + crq->item = cache_get(h); list_add_tail(&crq->q.list, &detail->queue); - else + } else /* Lost a race, no longer PENDING, so don't enqueue */ ret = -EAGAIN; spin_unlock(&queue_lock);