From: Karsten Graul <kgraul@linux.ibm.com>
Subject: net/smc: remove sock_error detour in clc-functions
Patch-mainline: v5.0-rc1
Git-commit: 6ae36bff3f511d8b24ebbc126e3f1f23ac202ef4
References: FATE#325698, LTC#167867, bsc#1113481

Description:  net/smc: bugfix and compatibility patches
Symptom:      Random hangs in smc processing:
                user space application hangs in socket send() or recv() call or
                does never get a notification from a select() call.
              Missing compatibility to other platforms:
                confirm rkey and delete rkey processing is required by the
                design, but delete rkey processing is missing. This leads to
                protocol failures when communicating with other platforms like
                zOS. The SMC-D shutdown signal support is missing, so there is
                no detection if the remote peer closed the link group.
              Broken administration of available WR send payload buffers due to
              a use-after-free condition.
Problem:      Misbehaviour regarding the user space api can lead to hang
              situations. SMC is not fully compatible to some other platforms
              due to missing rkey processing and SMC-D shutdown signal support.
Solution:     Fixed protocoll deficiencies by implementing the required rkey
              processing. For SMC-D, the cursors are now handled atomically to
              handle parallel modifications. The SMC-D shutdown signal is now
              processed when received and sent to the remote peer if needed.
              Prereq patches are included.
Reproduction: Run SMC on a loaded system against zOS as peer system.

Upstream-Description:

              net/smc: remove sock_error detour in clc-functions

              There is no need to store the return value in sk_err, if it is
              afterwards cleared again with sock_error(). This patch sets the
              return value directly. Just cleanup, no functional change.

              Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
              Signed-off-by: David S. Miller <davem@davemloft.net>


Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 net/smc/smc_clc.c |   18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

--- a/net/smc/smc_clc.c
+++ b/net/smc/smc_clc.c
@@ -373,10 +373,8 @@ int smc_clc_send_decline(struct smc_sock
 	len = kernel_sendmsg(smc->clcsock, &msg, &vec, 1,
 			     sizeof(struct smc_clc_msg_decline));
 	if (len < sizeof(struct smc_clc_msg_decline))
-		smc->sk.sk_err = EPROTO;
-	if (len < 0)
-		smc->sk.sk_err = -len;
-	return sock_error(&smc->sk);
+		len = -EPROTO;
+	return len > 0 ? 0 : len;
 }
 
 /* send CLC PROPOSAL message across internal TCP socket */
@@ -535,7 +533,6 @@ int smc_clc_send_accept(struct smc_sock
 	struct smc_link *link;
 	struct msghdr msg;
 	struct kvec vec;
-	int rc = 0;
 	int len;
 
 	memset(&aclc, 0, sizeof(aclc));
@@ -588,13 +585,8 @@ int smc_clc_send_accept(struct smc_sock
 	vec.iov_len = ntohs(aclc.hdr.length);
 	len = kernel_sendmsg(new_smc->clcsock, &msg, &vec, 1,
 			     ntohs(aclc.hdr.length));
-	if (len < ntohs(aclc.hdr.length)) {
-		if (len >= 0)
-			new_smc->sk.sk_err = EPROTO;
-		else
-			new_smc->sk.sk_err = new_smc->clcsock->sk->sk_err;
-		rc = sock_error(&new_smc->sk);
-	}
+	if (len < ntohs(aclc.hdr.length))
+		len = len >= 0 ? -EPROTO : -new_smc->clcsock->sk->sk_err;
 
-	return rc;
+	return len > 0 ? 0 : len;
 }