Commit 693486d5 authored by NeilBrown's avatar NeilBrown Committed by Trond Myklebust
Browse files

SUNRPC: change locking for xs_swap_enable/disable 



It is not in general safe to wait for XPRT_LOCKED to clear.
A wakeup is only sent when
 - connection completes
 - sock close completes
so during normal operations, this can wait indefinitely.

The event we need to protect against is ->inet being set to NULL, and
that happens under the recv_mutex lock.

So drop the handlign of XPRT_LOCKED and use recv_mutex instead.

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent c265de25

net/sunrpc/xprtsock.c

+11 −15
Original line number Diff line number Diff line
@@ -1936,9 +1936,9 @@ 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.

 * Note that this should be called with XPRT_LOCKED held, or recv_mutex

 * 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)

{
@@ -1967,13 +1967,11 @@ xs_enable_swap(struct rpc_xprt *xprt) 
{

	struct sock_xprt *xs = container_of(xprt, struct sock_xprt, xprt);



	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)

	mutex_lock(&xs->recv_mutex);

	if (atomic_inc_return(&xprt->swapper) == 1 &&

	    xs->inet)

		sk_set_memalloc(xs->inet);

	xprt_release_xprt(xprt, NULL);

	mutex_unlock(&xs->recv_mutex);

	return 0;

}
@@ -1989,13 +1987,11 @@ xs_disable_swap(struct rpc_xprt *xprt) 
{

	struct sock_xprt *xs = container_of(xprt, struct sock_xprt, xprt);



	if (!atomic_dec_and_test(&xprt->swapper))

		return;

	if (wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_KILLABLE))

		return;

	if (xs->inet)

	mutex_lock(&xs->recv_mutex);

	if (atomic_dec_and_test(&xprt->swapper) &&

	    xs->inet)

		sk_clear_memalloc(xs->inet);

	xprt_release_xprt(xprt, NULL);

	mutex_unlock(&xs->recv_mutex);

}

#else

static void xs_set_memalloc(struct rpc_xprt *xprt)