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Subject[PATCH] staging: lustre: lnet: Fix recent breakage from list_for_each conversion

Commit 8e55b6fd0660 ("staging: lustre: lnet: replace list_for_each
with list_for_each_entry") was intended to be an idempotent change,
but actually broke the behavior of ksocknal_add_peer() causing mounts to fail.
The fact that it caused an existing "route2 = NULL;" to become
redundant could have been a clue. The fact that the loop body
set the new loop variable to NULL might also have been a clue

The original code relied on "route2" being NULL if nothing was found.
The new code would always set route2 to a non-NULL value if the list
was empty, and would likely crash if the list was not empty.

Restore correct functionality by using code-flow rather the value of
"route2" to determine whether to use on old route, or to add a new one.

Fixes: 8e55b6fd0660 ("staging: lustre: lnet: replace list_for_each with list_for_each_entry")
Signed-off-by: NeilBrown <neilb@suse.com>
---
.../staging/lustre/lnet/klnds/socklnd/socklnd.c | 23 ++++++++++------------
1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/drivers/staging/lustre/lnet/klnds/socklnd/socklnd.c b/drivers/staging/lustre/lnet/klnds/socklnd/socklnd.c
index 9c92a83f214a..634c0cc7909f 100644
--- a/drivers/staging/lustre/lnet/klnds/socklnd/socklnd.c
+++ b/drivers/staging/lustre/lnet/klnds/socklnd/socklnd.c
@@ -487,21 +487,18 @@ ksocknal_add_peer(struct lnet_ni *ni, struct lnet_process_id id, __u32 ipaddr,
ksocknal_nid2peerlist(id.nid));
}

- route2 = NULL;
list_for_each_entry(route2, &peer->ksnp_routes, ksnr_list) {
- if (route2->ksnr_ipaddr == ipaddr)
- break;
-
- route2 = NULL;
- }
- if (!route2) {
- ksocknal_add_route_locked(peer, route);
- route->ksnr_share_count++;
- } else {
- ksocknal_route_decref(route);
- route2->ksnr_share_count++;
+ if (route2->ksnr_ipaddr == ipaddr) {
+ /* Route already exists, use the old one */
+ ksocknal_route_decref(route);
+ route2->ksnr_share_count++;
+ goto out;
+ }
}
-
+ /* Route doesn't already exist, add the new one */
+ ksocknal_add_route_locked(peer, route);
+ route->ksnr_share_count++;
+out:
write_unlock_bh(&ksocknal_data.ksnd_global_lock);

return 0;
--
2.14.0.rc0.dirty
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