linux-kernel - [PATCH review for 3.18 12/30] IB/ipoib: Replace list_del of the neigh->list with list_del

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Date:   Wed, 20 Sep 2017 04:45:52 +0000
From:   "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     Feras Daoud <ferasda@...lanox.com>,
        Erez Shitrit <erezsh@...lanox.com>,
        Leon Romanovsky <leon@...nel.org>,
        Doug Ledford <dledford@...hat.com>,
        "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com>
Subject: [PATCH review for 3.18 12/30] IB/ipoib: Replace list_del of the
 neigh->list with list_del_init

From: Feras Daoud <ferasda@...lanox.com>

[ Upstream commit c586071d1dc8227a7182179b8e50ee92cc43f6d2 ]

In order to resolve a situation where a few process delete
the same list element in sequence and cause panic, list_del
is replaced with list_del_init. In this case if the first
process that calls list_del releases the lock before acquiring
it again, other processes who can acquire the lock will call
list_del_init.

Fixes: b63b70d87741 ("IPoIB: Use a private hash table for path lookup")
Signed-off-by: Feras Daoud <ferasda@...lanox.com>
Signed-off-by: Erez Shitrit <erezsh@...lanox.com>
Reviewed-by: Alex Vesker <valex@...lanox.com>
Signed-off-by: Leon Romanovsky <leon@...nel.org>
Reviewed-by: Yuval Shaia <yuval.shaia@...cle.com>
Signed-off-by: Doug Ledford <dledford@...hat.com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
---
 drivers/infiniband/ulp/ipoib/ipoib_main.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c
index 5e08db6f9d8c..eab9eda0e7bd 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
@@ -958,7 +958,7 @@ static void __ipoib_reap_neigh(struct ipoib_dev_priv *priv)
 						   rcu_dereference_protected(neigh->hnext,
 									     lockdep_is_held(&priv->lock)));
 				/* remove from path/mc list */
-				list_del(&neigh->list);
+				list_del_init(&neigh->list);
 				call_rcu(&neigh->rcu, ipoib_neigh_reclaim);
 			} else {
 				np = &neigh->hnext;
@@ -1121,7 +1121,7 @@ void ipoib_neigh_free(struct ipoib_neigh *neigh)
 					   rcu_dereference_protected(neigh->hnext,
 								     lockdep_is_held(&priv->lock)));
 			/* remove from parent list */
-			list_del(&neigh->list);
+			list_del_init(&neigh->list);
 			call_rcu(&neigh->rcu, ipoib_neigh_reclaim);
 			return;
 		} else {
@@ -1206,7 +1206,7 @@ void ipoib_del_neighs_by_gid(struct net_device *dev, u8 *gid)
 						   rcu_dereference_protected(neigh->hnext,
 									     lockdep_is_held(&priv->lock)));
 				/* remove from parent list */
-				list_del(&neigh->list);
+				list_del_init(&neigh->list);
 				call_rcu(&neigh->rcu, ipoib_neigh_reclaim);
 			} else {
 				np = &neigh->hnext;
@@ -1248,7 +1248,7 @@ static void ipoib_flush_neighs(struct ipoib_dev_priv *priv)
 					   rcu_dereference_protected(neigh->hnext,
 								     lockdep_is_held(&priv->lock)));
 			/* remove from path/mc list */
-			list_del(&neigh->list);
+			list_del_init(&neigh->list);
 			call_rcu(&neigh->rcu, ipoib_neigh_reclaim);
 		}
 	}
-- 
2.11.0