From: NeilBrown <neilb@xxxxxxxx>
This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit a6ab1e8126d205238defbb55d23661a3a5c6a0d8 ]
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@xxxxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
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 14d38ec..11e7b55 100644
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -1187,14 +1187,14 @@ 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);
--
2.5.0
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