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

From: Levin, Alexander (Sasha Levin)
Date: Wed Sep 20 2017 - 00:46:25 EST


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>
---
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