Commit af84537d authored by Benjamin Coddington's avatar Benjamin Coddington Committed by Anna Schumaker
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SUNRPC: fix race to sk_err after xs_error_report 



Since commit 4f8943f8 ("SUNRPC: Replace direct task wakeups from
softirq context") there has been a race to the value of the sk_err if both
XPRT_SOCK_WAKE_ERROR and XPRT_SOCK_WAKE_DISCONNECT are set.  In that case,
we may end up losing the sk_err value that existed when xs_error_report was
called.

Fix this by reverting to the previous behavior: instead of using SO_ERROR
to retrieve the value at a later time (which might also return sk_err_soft),
copy the sk_err value onto struct sock_xprt, and use that value to wake
pending tasks.

Signed-off-by: default avatarBenjamin Coddington <bcodding@redhat.com>
Fixes: 4f8943f8 ("SUNRPC: Replace direct task wakeups from softirq context")
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent 1047ec86

include/linux/sunrpc/xprtsock.h

+1 −0
Original line number Diff line number Diff line
@@ -61,6 +61,7 @@ struct sock_xprt { 
	struct mutex		recv_mutex;

	struct sockaddr_storage	srcaddr;

	unsigned short		srcport;

	int			xprt_err;



	/*

	 * UDP socket buffer size parameters

net/sunrpc/xprtsock.c

+8 −9
Original line number Diff line number Diff line
@@ -1249,19 +1249,21 @@ static void xs_error_report(struct sock *sk) 
{

	struct sock_xprt *transport;

	struct rpc_xprt *xprt;

	int err;



	read_lock_bh(&sk->sk_callback_lock);

	if (!(xprt = xprt_from_sock(sk)))

		goto out;



	transport = container_of(xprt, struct sock_xprt, xprt);

	err = -sk->sk_err;

	if (err == 0)

	transport->xprt_err = -sk->sk_err;

	if (transport->xprt_err == 0)

		goto out;

	dprintk("RPC:       xs_error_report client %p, error=%d...\n",

			xprt, -err);

	trace_rpc_socket_error(xprt, sk->sk_socket, err);

			xprt, -transport->xprt_err);

	trace_rpc_socket_error(xprt, sk->sk_socket, transport->xprt_err);



	/* barrier ensures xprt_err is set before XPRT_SOCK_WAKE_ERROR */

	smp_mb__before_atomic();

	xs_run_error_worker(transport, XPRT_SOCK_WAKE_ERROR);

 out:

	read_unlock_bh(&sk->sk_callback_lock);
@@ -2476,7 +2478,6 @@ static void xs_wake_write(struct sock_xprt *transport) 
static void xs_wake_error(struct sock_xprt *transport)

{

	int sockerr;

	int sockerr_len = sizeof(sockerr);



	if (!test_bit(XPRT_SOCK_WAKE_ERROR, &transport->sock_state))

		return;
@@ -2485,9 +2486,7 @@ static void xs_wake_error(struct sock_xprt *transport) 
		goto out;

	if (!test_and_clear_bit(XPRT_SOCK_WAKE_ERROR, &transport->sock_state))

		goto out;

	if (kernel_getsockopt(transport->sock, SOL_SOCKET, SO_ERROR,

				(char *)&sockerr, &sockerr_len) != 0)

		goto out;

	sockerr = xchg(&transport->xprt_err, 0);

	if (sockerr < 0)

		xprt_wake_pending_tasks(&transport->xprt, sockerr);

out:

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