[PATCH 4.9 036/104] IB/ipoib: Replace list_del of the neigh->list with list_del_init

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Feras Daoud <ferasda@xxxxxxxxxxxx>


[ 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@xxxxxxxxxxxx>
Signed-off-by: Erez Shitrit <erezsh@xxxxxxxxxxxx>
Reviewed-by: Alex Vesker <valex@xxxxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leon@xxxxxxxxxx>
Reviewed-by: Yuval Shaia <yuval.shaia@xxxxxxxxxx>
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/infiniband/ulp/ipoib/ipoib_main.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
@@ -1302,7 +1302,7 @@ static void __ipoib_reap_neigh(struct ip
 						   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;
@@ -1466,7 +1466,7 @@ void ipoib_neigh_free(struct ipoib_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 {
@@ -1551,7 +1551,7 @@ void ipoib_del_neighs_by_gid(struct net_
 						   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;
@@ -1593,7 +1593,7 @@ static void ipoib_flush_neighs(struct ip
 					   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);
 		}
 	}