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Commit e47db94e authored by santosh.shilimkar@oracle.com's avatar santosh.shilimkar@oracle.com Committed by David S. Miller
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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: default avatarLeon Romanovsky <leon@leon.nu>
Signed-off-by: default avatarWengang Wang <wen.gang.wang@oracle.com>
Signed-off-by: default avatarSantosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a7c55654

net/rds/cong.c

+2 −2
Original line number Diff line number Diff line
@@ -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)