SUNRPC: Lock the transport layer on shutdown

Avoid all races with the connect/disconnect handlers by taking the
transport lock.

Reported-by:"Suzuki K. Poulose" <suzuki.poulose@arm.com>
Acked-by: Jeff Layton <jlayton@poochiereds.net>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index ab5dd621ae0c0795a0d86e1a9fb83c5cc2812486..2e98f4a243e57d4539b3f4048d54c4b53f3c12d5 100644 (file)
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -614,6 +614,7 @@ static void xprt_autoclose(struct work_struct *work)
        clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
        xprt->ops->close(xprt);
        xprt_release_write(xprt, NULL);
+       wake_up_bit(&xprt->state, XPRT_LOCKED);
 }
 
 /**
@@ -723,6 +724,7 @@ void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
        xprt->ops->release_xprt(xprt, NULL);
 out:
        spin_unlock_bh(&xprt->transport_lock);
+       wake_up_bit(&xprt->state, XPRT_LOCKED);
 }
 
 /**
@@ -1394,6 +1396,10 @@ out:
 static void xprt_destroy(struct rpc_xprt *xprt)
 {
        dprintk("RPC:       destroying transport %p\n", xprt);
+
+       /* Exclude transport connect/disconnect handlers */
+       wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
+
        del_timer_sync(&xprt->timer);
 
        rpc_xprt_debugfs_unregister(xprt);