Commit 0a9a4304 authored Dec 01, 2018 by Trond Myklebust

SUNRPC: Fix a potential race in xprt_connect()

If an asynchronous connection attempt completes while another task is
in xprt_connect(), then the call to rpc_sleep_on() could end up
racing with the call to xprt_wake_pending_tasks().
So add a second test of the connection state after we've put the
task to sleep and set the XPRT_CONNECTING flag, when we know that there
can be no asynchronous connection attempts still in progress.

Fixes: 0b9e7943 ("SUNRPC: Move the test for XPRT_CONNECTING into...")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

parent 71700bb9

net/sunrpc/xprt.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -826,8 +826,15 @@ void xprt_connect(struct rpc_task *task)
		return;
		if (xprt_test_and_set_connecting(xprt))
		return;
		/* Race breaker */
		if (!xprt_connected(xprt)) {
		xprt->stat.connect_start = jiffies;
		xprt->ops->connect(xprt, task);
		} else {
		xprt_clear_connecting(xprt);
		task->tk_status = 0;
		rpc_wake_up_queued_task(&xprt->pending, task);
		}
		}
		xprt_release_write(xprt, task);
		}