From: Karsten Graul <kgraul@linux.ibm.com>
Subject: net/smc: avoid a delay by waiting for nothing
Patch-mainline: v5.0-rc1
Git-commit: 4600cfc302f70f2b4d89818b4d4c79bd19e5ab87
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: avoid a delay by waiting for nothing
When a send failed then don't start to wait for a response in
smc_llc_do_confirm_rkey.
Signed-off-by: Karsten Graul <kgraul@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/smc_llc.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/net/smc/smc_llc.c
+++ b/net/smc/smc_llc.c
@@ -650,7 +650,9 @@ int smc_llc_do_confirm_rkey(struct smc_l
int rc;
reinit_completion(&link->llc_confirm_rkey);
- smc_llc_send_confirm_rkey(link, rmb_desc);
+ rc = smc_llc_send_confirm_rkey(link, rmb_desc);
+ if (rc)
+ return rc;
/* receive CONFIRM RKEY response from server over RoCE fabric */
rc = wait_for_completion_interruptible_timeout(&link->llc_confirm_rkey,
SMC_LLC_WAIT_TIME);