netdev - [PATCH net-next 3/6] net/smc: do not delete lgr from list twice

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Date:   Mon, 17 Feb 2020 16:24:52 +0100
From:   Ursula Braun <ubraun@...ux.ibm.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, linux-s390@...r.kernel.org,
        heiko.carstens@...ibm.com, raspl@...ux.ibm.com,
        kgraul@...ux.ibm.com, ubraun@...ux.ibm.com
Subject: [PATCH net-next 3/6] net/smc: do not delete lgr from list twice

From: Karsten Graul <kgraul@...ux.ibm.com>

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@...ux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@...ux.ibm.com>
---
 net/smc/smc_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index 8f3c1fced334..9b92b52952dd 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -629,7 +629,7 @@ void smc_lgr_terminate(struct smc_link_group *lgr, bool soft)

 	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 */
 	}
-- 
2.17.1