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| author | Andy Grover <andy.grover@oracle.com> | 2009-10-30 08:51:54 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-10-30 15:06:38 -0700 |
| commit | 86357b19bcabd9355937f3fb84f90ba9fe76a5d3 (patch) | |
| tree | ec9dfe857ce9d5c807b7cce4cd0c831c8e1fcdee /net/rds/ib_recv.c | |
| parent | 244546f0d3101c5441f5b14cfe8a79d62679eaea (diff) | |
| download | linux-86357b19bcabd9355937f3fb84f90ba9fe76a5d3.tar.gz linux-86357b19bcabd9355937f3fb84f90ba9fe76a5d3.tar.bz2 linux-86357b19bcabd9355937f3fb84f90ba9fe76a5d3.zip | |
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.c | 7 |
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); } |