SUNRPC: Don't take transport->lock unnecessarily when taking XPRT_LOCK

Trond Myklebust · Trond Myklebust · commit bd79bc579ca5 · 2018-09-30T15:35:16.000-04:00
Signed-off-by: Trond Myklebust &lt;trond.myklebust@hammerspace.com&gt;
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
@@ -298,6 +298,8 @@ static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
 {
 	int retval;
 
+	if (test_bit(XPRT_LOCKED, &xprt->state) && xprt->snd_task == task)
+		return 1;
 	spin_lock_bh(&xprt->transport_lock);
 	retval = xprt->ops->reserve_xprt(xprt, task);
 	spin_unlock_bh(&xprt->transport_lock);
@@ -375,6 +377,8 @@ EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
 
 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
 {
+	if (xprt->snd_task != task)
+		return;
 	spin_lock_bh(&xprt->transport_lock);
 	xprt->ops->release_xprt(xprt, task);
 	spin_unlock_bh(&xprt->transport_lock);
@@ -1645,8 +1649,7 @@ void xprt_release(struct rpc_task *task)
 	if (req == NULL) {
 		if (task->tk_client) {
 			xprt = task->tk_xprt;
-			if (xprt->snd_task == task)
-				xprt_release_write(xprt, task);
+			xprt_release_write(xprt, task);
 		}
 		return;
 	}

Original file line number	Diff line number	Diff line change
`@@ -298,6 +298,8 @@ static inline int xprt_lock_write(struct rpc_xprt xprt, struct rpc_task task)`
`298`	`298`	`{`
`299`	`299`	`int retval;`
`300`	`300`
	`301`	`+ if (test_bit(XPRT_LOCKED, &xprt->state) && xprt->snd_task == task)`
	`302`	`+ return 1;`
`301`	`303`	`spin_lock_bh(&xprt->transport_lock);`
`302`	`304`	`retval = xprt->ops->reserve_xprt(xprt, task);`
`303`	`305`	`spin_unlock_bh(&xprt->transport_lock);`
`@@ -375,6 +377,8 @@ EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);`
`375`	`377`
`376`	`378`	`static inline void xprt_release_write(struct rpc_xprt xprt, struct rpc_task task)`
`377`	`379`	`{`
	`380`	`+ if (xprt->snd_task != task)`
	`381`	`+ return;`
`378`	`382`	`spin_lock_bh(&xprt->transport_lock);`
`379`	`383`	`xprt->ops->release_xprt(xprt, task);`
`380`	`384`	`spin_unlock_bh(&xprt->transport_lock);`
`@@ -1645,8 +1649,7 @@ void xprt_release(struct rpc_task *task)`
`1645`	`1649`	`if (req == NULL) {`
`1646`	`1650`	`if (task->tk_client) {`
`1647`	`1651`	`xprt = task->tk_xprt;`
`1648`		`- if (xprt->snd_task == task)`
`1649`		`- xprt_release_write(xprt, task);`
	`1652`	`+ xprt_release_write(xprt, task);`
`1650`	`1653`	`}`
`1651`	`1654`	`return;`
`1652`	`1655`	`}`