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| author | NeilBrown <neilb@suse.com> | 2016-03-04 17:20:13 +1100 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2016-05-03 07:45:09 +0200 |
| commit | 6fa6f0c4ca2752a42bb03b41bffb4556b5ccec8c (patch) | |
| tree | 5eb09da6ded462d9a55e7db151d921bd6e2af74b /net | |
| parent | b4a6367c6632234a8241d0c1f39405dffb90769e (diff) | |
| download | lwn-6fa6f0c4ca2752a42bb03b41bffb4556b5ccec8c.tar.gz lwn-6fa6f0c4ca2752a42bb03b41bffb4556b5ccec8c.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: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'net')
| -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 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); |