diff options
author | Tina Yang <tina.yang@oracle.com> | 2010-04-01 17:09:00 -0400 |
---|---|---|
committer | Andy Grover <andy.grover@oracle.com> | 2010-09-08 21:07:31 -0400 |
commit | 35b52c70534cb7193b218ec12efe6bc595312097 (patch) | |
tree | 8370e4b3e9d0ed1cc353f8b23531c97f8cc63ddc /net/rds/iw_rdma.c | |
parent | 9e2effba2c16fc3bd47da605116485afe01e0be0 (diff) |
RDS: Fix corrupted rds_mrs
On second look at this bug (OFED #2002), it seems that the
collision is not with the retransmission queue (packet acked
by the peer), but with the local send completion. A theoretical
sequence of events (from time t0 to t3) is thought to be as
follows,
Thread #1
t0:
sock_release
rds_release
rds_send_drop_to /* wait on send completion */
t2:
rds_rdma_drop_keys() /* destroy & free all mrs */
Thread #2
t1:
rds_ib_send_cq_comp_handler
rds_ib_send_unmap_rm
rds_message_unmapped /* wake up #1 @ t0 */
t3:
rds_message_put
rds_message_purge
rds_mr_put /* memory corruption detected */
The problem with the rds_rdma_drop_keys() is it could
remove a mr's refcount more than its due (i.e. repeatedly
as long as it still remains in the tree (mr->r_refcount > 0)).
Theoretically it should remove only one reference - reference
by the tree.
/* Release any MRs associated with this socket */
while ((node = rb_first(&rs->rs_rdma_keys))) {
mr = container_of(node, struct rds_mr, r_rb_node);
if (mr->r_trans == rs->rs_transport)
mr->r_invalidate = 0;
rds_mr_put(mr);
}
I think the correct way of doing it is to remove the mr from
the tree and rds_destroy_mr it first, then a rds_mr_put()
to decrement its reference count by one. Whichever thread
holds the last reference will free the mr via rds_mr_put().
Signed-off-by: Tina Yang <tina.yang@oracle.com>
Signed-off-by: Andy Grover <andy.grover@oracle.com>
Diffstat (limited to 'net/rds/iw_rdma.c')
0 files changed, 0 insertions, 0 deletions