Subject: [PATCH 16/43] rhashtable: Fix rhlist duplicates insertion

From: Paul Blakey <[email-masked]>
Date: Sun, 4 Mar 2018 17:29:48 +0200

[ Upstream commit d3dcf8eb615537526bd42ff27a081d46d337816e ]

When inserting duplicate objects (those with the same key),
current rhlist implementation messes up the chain pointers by
updating the bucket pointer instead of prev next pointer to the
newly inserted node. This causes missing elements on removal and
travesal.

Fix that by properly updating pprev pointer to point to
the correct rhash_head next pointer.

Issue: 1241076
Change-Id: I86b2c140bcb4aeb10b70a72a267ff590bb2b17e7
Fixes: ca26893f05e8 ('rhashtable: Add rhlist interface')
Signed-off-by: Paul Blakey <[email-masked]>
Acked-by: Herbert Xu <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 include/linux/rhashtable.h | 4 +++-
 lib/rhashtable.c           | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index 361c08e35dbc..7fd514f36e74 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -750,8 +750,10 @@ static inline void *__rhashtable_insert_fast(
 		if (!key ||
 		    (params.obj_cmpfn ?
 		     params.obj_cmpfn(&arg, rht_obj(ht, head)) :
-		     rhashtable_compare(&arg, rht_obj(ht, head))))
+		     rhashtable_compare(&arg, rht_obj(ht, head)))) {
+			pprev = &head->next;
 			continue;
+		}
 
 		data = rht_obj(ht, head);
 
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index ddd7dde87c3c..b734ce731a7a 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -537,8 +537,10 @@ static void *rhashtable_lookup_one(struct rhashtable *ht,
 		if (!key ||
 		    (ht->p.obj_cmpfn ?
 		     ht->p.obj_cmpfn(&arg, rht_obj(ht, head)) :
-		     rhashtable_compare(&arg, rht_obj(ht, head))))
+		     rhashtable_compare(&arg, rht_obj(ht, head)))) {
+			pprev = &head->next;
 			continue;
+		}
 
 		if (!ht->rhlist)
 			return rht_obj(ht, head);
-- 
2.14.3