From: Karsten Graul <kgraul@linux.ibm.com>
Date: Mon, 17 Feb 2020 16:24:52 +0100
Subject: net/smc: do not delete lgr from list twice
Git-commit: 3739707c4568f05842c8bf770285328067bd6679
Patch-mainline: v5.7-rc1
References: jsc#SLE-13763

When 2 callers call smc_lgr_terminate() at the same time
for the same lgr, one gets the lgr_lock and deletes the lgr from the
list and releases the lock. Then the second caller gets the lock and
tries to delete it again.
In smc_lgr_terminate() add a check if the link group lgr is already
deleted from the link group list and prevent to try to delete it a
second time.
And add a check if the lgr is marked as freeing, which means that a
termination is already pending.

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>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 net/smc/smc_core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -641,7 +641,7 @@ void smc_lgr_terminate(struct smc_link_g
 
 	smc_lgr_list_head(lgr, &lgr_lock);
 	spin_lock_bh(lgr_lock);
-	if (lgr->terminating) {
+	if (list_empty(&lgr->list) || lgr->terminating || lgr->freeing) {
 		spin_unlock_bh(lgr_lock);
 		return;	/* lgr already terminating */
 	}