linux-kernel - [PATCH AUTOSEL for 4.15 018/189] xprtrdma: Eliminate unnecessary lock cycle in xprt_rdma_send

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Message-ID: <20180409001637.162453-18-alexander.levin@microsoft.com>
Date:   Mon, 9 Apr 2018 00:16:58 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Chuck Lever <chuck.lever@...cle.com>,
        Anna Schumaker <Anna.Schumaker@...app.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.15 018/189] xprtrdma: Eliminate unnecessary lock
 cycle in xprt_rdma_send_request

From: Chuck Lever <chuck.lever@...cle.com>

[ Upstream commit 42b9f5c58aa8c59c91ead0254f0c193e3438b020 ]

The rpcrdma_req is not shared yet, and its associated Send hasn't
been posted, thus RMW should be safe. There's no need for the
expense of a lock cycle here.

Fixes: 0ba6f37012db ("xprtrdma: Refactor rpcrdma_deferred_completion")
Signed-off-by: Chuck Lever <chuck.lever@...cle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@...app.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 net/sunrpc/xprtrdma/transport.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index 6ee1ad8978f3..76c03aa6cb57 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -744,7 +744,7 @@ xprt_rdma_send_request(struct rpc_task *task)
 		goto drop_connection;
 	req->rl_connect_cookie = xprt->connect_cookie;
 
-	set_bit(RPCRDMA_REQ_F_PENDING, &req->rl_flags);
+	__set_bit(RPCRDMA_REQ_F_PENDING, &req->rl_flags);
 	if (rpcrdma_ep_post(&r_xprt->rx_ia, &r_xprt->rx_ep, req))
 		goto drop_connection;
 
-- 
2.15.1