Patch "RDS: Fix the atomicity for congestion map update" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

RDS: Fix the atomicity for congestion map update

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
rds-fix-the-atomicity-for-congestion-map-update.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: "[email protected]" <[email protected]>
Date: Thu, 14 Apr 2016 10:43:27 -0700
Subject: RDS: Fix the atomicity for congestion map update

From: [email protected] <[email protected]>

commit e47db94e10447fc467777a40302f2b393e9af2fa upstream.

Two different threads with different rds sockets may be in rds_recv_rcvbuf_delta() via receive path. If their ports both map to the same word in the congestion map, then using non-atomic ops to update it could cause the map to be incorrect. Lets use atomics to avoid such an issue.

Full credit to Wengang <[email protected]> for finding the issue, analysing it and also pointing out to offending code with spin lock based fix.

---
 net/rds/cong.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -299,7 +299,7 @@ void rds_cong_set_bit(struct rds_cong_ma
 	i = be16_to_cpu(port) / RDS_CONG_MAP_PAGE_BITS;
 	off = be16_to_cpu(port) % RDS_CONG_MAP_PAGE_BITS;
 
-	__set_bit_le(off, (void *)map->m_page_addrs[i]);
+	set_bit_le(off, (void *)map->m_page_addrs[i]);
 }
 
 void rds_cong_clear_bit(struct rds_cong_map *map, __be16 port)

@@ -313,7 +313,7 @@ void rds_cong_clear_bit(struct rds_cong_
 	i = be16_to_cpu(port) / RDS_CONG_MAP_PAGE_BITS;
 	off = be16_to_cpu(port) % RDS_CONG_MAP_PAGE_BITS;
 
-	__clear_bit_le(off, (void *)map->m_page_addrs[i]);
+	clear_bit_le(off, (void *)map->m_page_addrs[i]);
 }
 
 static int rds_cong_test_bit(struct rds_cong_map *map, __be16 port)

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/rds-fix-the-atomicity-for-congestion-map-update.patch