From: Karsten Graul <kgraul@linux.ibm.com>
Subject: net/smc: abort CLC connection in smc_release
Patch-mainline: v4.20-rc4
Git-commit: f07920ad9c6f5781c90ac4915f8254d999d8c1cc
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: abort CLC connection in smc_release

              In case of a non-blocking SMC socket, the initial CLC handshake is
              performed over a blocking TCP connection in a worker. If the SMC socket
              is released, smc_release has to wait for the blocking CLC socket
              operations (e.g., kernel_connect) inside the worker.

              This patch aborts a CLC connection when the respective non-blocking SMC
              socket is released to avoid waiting on socket operations or timeouts.

              Signed-off-by: Hans Wippel <hwippel@linux.ibm.com>
              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/af_smc.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -127,6 +127,8 @@ static int smc_release(struct socket *so
 	smc = smc_sk(sk);
 
 	/* cleanup for a dangling non-blocking connect */
+	if (smc->connect_info && sk->sk_state == SMC_INIT)
+		tcp_abort(smc->clcsock->sk, ECONNABORTED);
 	flush_work(&smc->connect_work);
 	kfree(smc->connect_info);
 	smc->connect_info = NULL;