[PATCH AUTOSEL 3.18 06/16] SUNRPC: Fix a potential race in xprt_connect()
From: Sasha Levin <sashal@kernel.org>
Date: 2018-12-13 04:35:35
Also in:
linux-nfs, lkml, stable
Subsystem:
kernel nfsd, sunrpc, and lockd servers, networking [general], nfs, sunrpc, and lockd clients, the rest · Maintainers:
Chuck Lever, Jeff Layton, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Trond Myklebust, Anna Schumaker, Linus Torvalds
From: Trond Myklebust <redacted>
[ Upstream commit 0a9a4304f3614e25d9de9b63502ca633c01c0d70 ]
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: 0b9e79431377d ("SUNRPC: Move the test for XPRT_CONNECTING into...")
Signed-off-by: Trond Myklebust <redacted>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/sunrpc/xprt.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 56e4e150e80e..dca234b1f77d 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c@@ -721,8 +721,15 @@ void xprt_connect(struct rpc_task *task) return; if (xprt_test_and_set_connecting(xprt)) return; - xprt->stat.connect_start = jiffies; - xprt->ops->connect(xprt, task); + /* 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); + } } }
--
2.19.1