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| author | NeilBrown <neilb@suse.com> | 2016-03-04 17:20:13 +1100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-05-04 14:49:15 -0700 |
| commit | 804dc5091dc709fe7cef2df53d7436f0ac0b0484 (patch) | |
| tree | 9501a608b434676f9eaf7efaad900fbb36fa3603 | |
| parent | ac4b17cf608c96fd1eecee5b0ca9cbcc8765b9d8 (diff) | |
| download | lwn-804dc5091dc709fe7cef2df53d7436f0ac0b0484.tar.gz lwn-804dc5091dc709fe7cef2df53d7436f0ac0b0484.zip | |
sunrpc/cache: drop reference when sunrpc_cache_pipe_upcall() detects a race
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/sunrpc/cache.c | 6 |
1 files changed, 3 insertions, 3 deletions
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); |