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authorAndy Grover <andy.grover@oracle.com>2009-10-30 08:51:54 +0000
committerDavid S. Miller <davem@davemloft.net>2009-10-30 15:06:38 -0700
commit86357b19bcabd9355937f3fb84f90ba9fe76a5d3 (patch)
treeec9dfe857ce9d5c807b7cce4cd0c831c8e1fcdee /net/rds/ib_recv.c
parent244546f0d3101c5441f5b14cfe8a79d62679eaea (diff)
downloadlinux-sh-86357b19bcabd9355937f3fb84f90ba9fe76a5d3.tar.gz
RDS: Fix potential race around rds_i[bw]_allocation
"At rds_ib_recv_refill_one(), it first executes atomic_read(&rds_ib_allocation) for if-condition checking, and then executes atomic_inc(&rds_ib_allocation) if the condition was not satisfied. However, if any other code which updates rds_ib_allocation executes between these two atomic operation executions, it seems that it may result race condition. (especially when rds_ib_allocation + 1 == rds_ib_sysctl_max_recv_allocation)" This patch fixes this by using atomic_inc_unless to eliminate the possibility of allocating more than rds_ib_sysctl_max_recv_allocation and then decrementing the count if the allocation fails. It also makes an identical change to the iwarp transport. Reported-by: Shin Hong <hongshin@gmail.com> Signed-off-by: Andy Grover <andy.grover@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/rds/ib_recv.c')
-rw-r--r--net/rds/ib_recv.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
index cd7a6cfcab03..2f009d391c29 100644
--- a/net/rds/ib_recv.c
+++ b/net/rds/ib_recv.c
@@ -143,15 +143,16 @@ static int rds_ib_recv_refill_one(struct rds_connection *conn,
int ret = -ENOMEM;
if (recv->r_ibinc == NULL) {
- if (atomic_read(&rds_ib_allocation) >= rds_ib_sysctl_max_recv_allocation) {
+ if (!atomic_add_unless(&rds_ib_allocation, 1, rds_ib_sysctl_max_recv_allocation)) {
rds_ib_stats_inc(s_ib_rx_alloc_limit);
goto out;
}
recv->r_ibinc = kmem_cache_alloc(rds_ib_incoming_slab,
kptr_gfp);
- if (recv->r_ibinc == NULL)
+ if (recv->r_ibinc == NULL) {
+ atomic_dec(&rds_ib_allocation);
goto out;
- atomic_inc(&rds_ib_allocation);
+ }
INIT_LIST_HEAD(&recv->r_ibinc->ii_frags);
rds_inc_init(&recv->r_ibinc->ii_inc, conn, conn->c_faddr);
}