RDS: Fix potential race around rds_i[bw]_allocation

[safe/jmp/linux-2.6] / net / rds / ib_recv.c

diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
index cd7a6cf..2f009d3 100644 (file)
--- 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);
        }