[PATCH 4.4 12/43] RDS: Fix the atomicity for congestion map update - Greg Kroah-Hartman

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Leon Romanovsky <leon@leon.nu>,
	Wengang Wang <wen.gang.wang@oracle.com>,
	Santosh Shilimkar <santosh.shilimkar@oracle.com>,
	"David S. Miller" <davem@davemloft.net>,
	Julia Lawall <julia.lawall@lip6.fr>
Subject: [PATCH 4.4 12/43] RDS: Fix the atomicity for congestion map update
Date: Mon,  1 May 2017 14:27:12 -0700	[thread overview]
Message-ID: <20170501212600.028205246@linuxfoundation.org> (raw)
In-Reply-To: <20170501212559.546911128@linuxfoundation.org>

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: santosh.shilimkar@oracle.com <santosh.shilimkar@oracle.com>

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 <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>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/net/rds/cong.c
+++ b/net/rds/cong.c
@@ -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)
