From: Karsten Graul <kgraul@linux.ibm.com>
Subject: net/smc: enable fallback for connection abort in state INIT
Patch-mainline: v4.19-rc6
Git-commit: dd65d87a6abd537ae9bb3bdcee8905704b936884
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: enable fallback for connection abort in state INIT

              If a linkgroup is terminated abnormally already due to failing
              LLC CONFIRM LINK or LLC ADD LINK, fallback to TCP is still possible.
              In this case do not switch to state SMC_PEERABORTWAIT and do not set
              sk_err.

              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_close.c |   14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

--- a/net/smc/smc_close.c
+++ b/net/smc/smc_close.c
@@ -99,15 +99,14 @@ static void smc_close_active_abort(struc
 	struct smc_cdc_conn_state_flags *txflags =
 		&smc->conn.local_tx_ctrl.conn_state_flags;
 
-	sk->sk_err = ECONNABORTED;
-	if (smc->clcsock && smc->clcsock->sk) {
-		smc->clcsock->sk->sk_err = ECONNABORTED;
-		smc->clcsock->sk->sk_state_change(smc->clcsock->sk);
+	if (sk->sk_state != SMC_INIT && smc->clcsock && smc->clcsock->sk) {
+		sk->sk_err = ECONNABORTED;
+		if (smc->clcsock && smc->clcsock->sk) {
+			smc->clcsock->sk->sk_err = ECONNABORTED;
+			smc->clcsock->sk->sk_state_change(smc->clcsock->sk);
+		}
 	}
 	switch (sk->sk_state) {
-	case SMC_INIT:
-		sk->sk_state = SMC_PEERABORTWAIT;
-		break;
 	case SMC_ACTIVE:
 		sk->sk_state = SMC_PEERABORTWAIT;
 		release_sock(sk);
@@ -142,6 +141,7 @@ static void smc_close_active_abort(struc
 	case SMC_PEERFINCLOSEWAIT:
 		sock_put(sk); /* passive closing */
 		break;
+	case SMC_INIT:
 	case SMC_PEERABORTWAIT:
 	case SMC_CLOSED:
 		break;