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

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

From: Feras Daoud <fera...@mellanox.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 <fera...@mellanox.com>
Signed-off-by: Erez Shitrit <ere...@mellanox.com>
Reviewed-by: Alex Vesker <va...@mellanox.com>
Signed-off-by: Leon Romanovsky <l...@kernel.org>
Reviewed-by: Yuval Shaia <yuval.sh...@oracle.com>
Signed-off-by: Doug Ledford <dledf...@redhat.com>
Signed-off-by: Sasha Levin <alexander.le...@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 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
@@ -1239,7 +1239,7 @@ 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;
@@ -1406,7 +1406,7 @@ 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 {
@@ -1491,7 +1491,7 @@ 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;
@@ -1533,7 +1533,7 @@ 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);
                }
        }


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