Messages in this thread Patch in this message | | | From | Jiri Slaby <> | Subject | [PATCH 3.12 26/76] sunrpc/cache: drop reference when sunrpc_cache_pipe_upcall() detects a race | Date | Thu, 19 May 2016 11:07:48 +0200 |
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From: NeilBrown <neilb@suse.com>
3.12-stable review patch. If anyone has any objections, please let me know.
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commit a6ab1e8126d205238defbb55d23661a3a5c6a0d8 upstream.
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 <neilb@suse.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz> --- net/sunrpc/cache.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c index f3e2b7d8f325..b81e0a33a8be 100644 --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -1189,14 +1189,14 @@ 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); -- 2.8.2
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