Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759200AbcDHW0w (ORCPT ); Fri, 8 Apr 2016 18:26:52 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:21715 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754261AbcDHW0u (ORCPT ); Fri, 8 Apr 2016 18:26:50 -0400 From: Santosh Shilimkar To: netdev@vger.kernel.org, davem@davemloft.net Cc: linux-kernel@vger.kernel.org, Santosh Shilimkar Subject: [net-next][PATCH 2/2] RDS: Fix the atomicity for congestion map update Date: Fri, 8 Apr 2016 15:26:40 -0700 Message-Id: <1460154400-14546-3-git-send-email-santosh.shilimkar@oracle.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1460154400-14546-1-git-send-email-santosh.shilimkar@oracle.com> References: <1460154400-14546-1-git-send-email-santosh.shilimkar@oracle.com> X-Source-IP: userv0021.oracle.com [156.151.31.71] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1524 Lines: 41 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 for finding the issue, analysing it and also pointing out to offending code with spin lock based fix. Reviewed-by: Leon Romanovsky Signed-off-by: Wengang Wang Signed-off-by: Santosh Shilimkar --- net/rds/cong.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/rds/cong.c b/net/rds/cong.c index e6144b8..6641bcf 100644 --- 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) -- 1.9.1