From: Jason Gunthorpe <jgg@mellanox.com>
Date: Wed, 27 Jun 2018 10:44:26 +0300
Subject: IB/cm: Remove now useless rcu_lock in dst_fetch_ha
Patch-mainline: v4.19-rc1
Git-commit: 92ebb6a0a13a698f88fb3ba58c01844f190d2af5
References: bsc#1103992 FATE#326009

This lock used to be protecting a call to dst_get_neighbour_noref,
however the below commit changed it to dst_neigh_lookup which no longer
requires rcu.

Access to nud_state, neigh_event_send or rdma_copy_addr does not require
RCU, so delete the lock.

Fixes: 02b619555ad6 ("infiniband: Convert dst_fetch_ha() over to dst_neigh_lookup().")
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/infiniband/core/addr.c |   12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

--- a/drivers/infiniband/core/addr.c
+++ b/drivers/infiniband/core/addr.c
@@ -315,19 +315,17 @@ static int dst_fetch_ha(const struct dst
 	int ret = 0;
 
 	n = dst_neigh_lookup(dst, daddr);
+	if (!n)
+		return -ENODATA;
 
-	rcu_read_lock();
-	if (!n || !(n->nud_state & NUD_VALID)) {
-		if (n)
-			neigh_event_send(n, NULL);
+	if (!(n->nud_state & NUD_VALID)) {
+		neigh_event_send(n, NULL);
 		ret = -ENODATA;
 	} else {
 		rdma_copy_addr(dev_addr, dst->dev, n->ha);
 	}
-	rcu_read_unlock();
 
-	if (n)
-		neigh_release(n);
+	neigh_release(n);
 
 	return ret;
 }