From: Stefan Raspl <stefan.raspl@linux.ibm.com>
Date: Thu, 3 May 2018 17:57:39 +0200
Subject: smc: fix sendpage() call
Patch-mainline: v4.17-rc4
Git-commit: bda27ff5c4526f80a7620a94ecfe8dca153e3696
References: bsc#1096003, FATE#325023, LTC#164003

The sendpage() call grabs the sock lock before calling the default
implementation - which tries to grab it once again.

Signed-off-by: Stefan Raspl <raspl@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com><
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
---
 net/smc/af_smc.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index d03b8d29ffc0..544bab42f925 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -1315,8 +1315,11 @@ static ssize_t smc_sendpage(struct socket *sock, struct page *page,
 
 	smc = smc_sk(sk);
 	lock_sock(sk);
-	if (sk->sk_state != SMC_ACTIVE)
+	if (sk->sk_state != SMC_ACTIVE) {
+		release_sock(sk);
 		goto out;
+	}
+	release_sock(sk);
 	if (smc->use_fallback)
 		rc = kernel_sendpage(smc->clcsock, page, offset,
 				     size, flags);
@@ -1324,7 +1327,6 @@ static ssize_t smc_sendpage(struct socket *sock, struct page *page,
 		rc = sock_no_sendpage(sock, page, offset, size, flags);
 
 out:
-	release_sock(sk);
 	return rc;
 }