RDS: Fix the atomicity for congestion map update

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 <wen.gang.wang@oracle.com> for
finding the issue, analysing it and also pointing out
to offending code with spin lock based fix.

Reviewed-by: Leon Romanovsky <leon@leon.nu>
Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/rds/cong.c b/net/rds/cong.c
index e6144b8..6641bcf 100644 (file)
--- a/net/rds/cong.c
+++ b/net/rds/cong.c
@@ -299,7 +299,7 @@ void rds_cong_set_bit(struct rds_cong_map *map, __be16 port)
        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_map *map, __be16 port)
        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)