Commit a6ab1e81 authored Mar 04, 2016 by NeilBrown Committed by J. Bruce Fields Mar 17, 2016

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: f9e1aedc ("sunrpc/cache: remove races with queuing an upcall.")
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

parent 956ccef3

net/sunrpc/cache.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -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);

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