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sunrpc: lock xprt before trying to set memalloc on the sockets

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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>
This commit is contained in:
Jeff Layton 2015-06-03 16:14:28 -04:00 committed by Trond Myklebust
parent 264d1df3b3
commit d6e971d8ec
1 changed files with 27 additions and 8 deletions
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35
net/sunrpc/xprtsock.c
View file

@ -1959,11 +1959,22 @@ static void xs_local_connect(struct rpc_xprt *xprt, struct rpc_task *task)
} }
#if IS_ENABLED(CONFIG_SUNRPC_SWAP) #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) static void xs_set_memalloc(struct rpc_xprt *xprt)
{ {
struct sock_xprt *transport = container_of(xprt, struct sock_xprt, struct sock_xprt *transport = container_of(xprt, struct sock_xprt,
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)) if (atomic_read(&xprt->swapper))
sk_set_memalloc(transport->inet); sk_set_memalloc(transport->inet);
} }
@ -1978,11 +1989,15 @@ static void xs_set_memalloc(struct rpc_xprt *xprt)
int int
xs_swapper_enable(struct rpc_xprt *xprt) xs_swapper_enable(struct rpc_xprt *xprt)
{ {
struct sock_xprt *transport = container_of(xprt, struct sock_xprt, struct sock_xprt *xs = container_of(xprt, struct sock_xprt, xprt);
xprt);
if (atomic_inc_return(&xprt->swapper) == 1) if (atomic_inc_return(&xprt->swapper) != 1)
sk_set_memalloc(transport->inet); 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; return 0;
} }
@ -1996,11 +2011,15 @@ xs_swapper_enable(struct rpc_xprt *xprt)
void void
xs_swapper_disable(struct rpc_xprt *xprt) xs_swapper_disable(struct rpc_xprt *xprt)
{ {
struct sock_xprt *transport = container_of(xprt, struct sock_xprt, struct sock_xprt *xs = container_of(xprt, struct sock_xprt, xprt);
xprt);
if (atomic_dec_and_test(&xprt->swapper)) if (!atomic_dec_and_test(&xprt->swapper))
sk_clear_memalloc(transport->inet); 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 #else
static void xs_set_memalloc(struct rpc_xprt *xprt) static void xs_set_memalloc(struct rpc_xprt *xprt)