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authorJeff Layton <jlayton@poochiereds.net>2015-06-03 16:14:28 -0400
committerTrond Myklebust <trond.myklebust@primarydata.com>2015-06-10 18:26:24 -0400
commitd6e971d8ecafee18ff9cc1ac646eb0817ab8b143 (patch)
treed1a2a975cee7cbe10258081e2a2a781a95d15a8f
parent264d1df3b34804a7d440d77771020f616a573528 (diff)
downloadop-kernel-dev-d6e971d8ecafee18ff9cc1ac646eb0817ab8b143.zip
op-kernel-dev-d6e971d8ecafee18ff9cc1ac646eb0817ab8b143.tar.gz
sunrpc: lock xprt before trying to set memalloc on the sockets
It's possible that we could race with a call to xs_reset_transport, in which case the xprt->inet pointer could be zeroed out while we're accessing it. Lock the xprt before we try to set memalloc on it. Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Jeff Layton <jeff.layton@primarydata.com> Reviewed-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
-rw-r--r--net/sunrpc/xprtsock.c35
1 files changed, 27 insertions, 8 deletions
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 31b856a..e0efd85 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1959,11 +1959,22 @@ static void xs_local_connect(struct rpc_xprt *xprt, struct rpc_task *task)
}
#if IS_ENABLED(CONFIG_SUNRPC_SWAP)
+/*
+ * Note that this should be called with XPRT_LOCKED held (or when we otherwise
+ * know that we have exclusive access to the socket), to guard against
+ * races with xs_reset_transport.
+ */
static void xs_set_memalloc(struct rpc_xprt *xprt)
{
struct sock_xprt *transport = container_of(xprt, struct sock_xprt,
xprt);
+ /*
+ * If there's no sock, then we have nothing to set. The
+ * reconnecting process will get it for us.
+ */
+ if (!transport->inet)
+ return;
if (atomic_read(&xprt->swapper))
sk_set_memalloc(transport->inet);
}
@@ -1978,11 +1989,15 @@ static void xs_set_memalloc(struct rpc_xprt *xprt)
int
xs_swapper_enable(struct rpc_xprt *xprt)
{
- struct sock_xprt *transport = container_of(xprt, struct sock_xprt,
- xprt);
+ struct sock_xprt *xs = container_of(xprt, struct sock_xprt, xprt);
- if (atomic_inc_return(&xprt->swapper) == 1)
- sk_set_memalloc(transport->inet);
+ if (atomic_inc_return(&xprt->swapper) != 1)
+ return 0;
+ if (wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_KILLABLE))
+ return -ERESTARTSYS;
+ if (xs->inet)
+ sk_set_memalloc(xs->inet);
+ xprt_release_xprt(xprt, NULL);
return 0;
}
@@ -1996,11 +2011,15 @@ xs_swapper_enable(struct rpc_xprt *xprt)
void
xs_swapper_disable(struct rpc_xprt *xprt)
{
- struct sock_xprt *transport = container_of(xprt, struct sock_xprt,
- xprt);
+ struct sock_xprt *xs = container_of(xprt, struct sock_xprt, xprt);
- if (atomic_dec_and_test(&xprt->swapper))
- sk_clear_memalloc(transport->inet);
+ if (!atomic_dec_and_test(&xprt->swapper))
+ return;
+ if (wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_KILLABLE))
+ return;
+ if (xs->inet)
+ sk_clear_memalloc(xs->inet);
+ xprt_release_xprt(xprt, NULL);
}
#else
static void xs_set_memalloc(struct rpc_xprt *xprt)
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