RDMA/mlx5: Fix prefetch memory leak if get_prefetchable_mr fails

destroy_prefetch_work() must always be called if the work is not going
to be queued. The num_sge also should have been set to i, not i-1
which avoids the condition where it shouldn't have been called in the
first place.

Cc: stable@vger.kernel.org
Fixes: fb985e278a30 ("RDMA/mlx5: Use SRCU properly in ODP prefetch")
Link: https://lore.kernel.org/r/20200727095712.495652-1-leon@kernel.org
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c
index 1ab676b6689408005eb357717e62f1b39b3b1bff..77dca1e05bba8db7dc40c6346855c84386302f4b 100644 (file)
--- a/drivers/infiniband/hw/mlx5/odp.c
+++ b/drivers/infiniband/hw/mlx5/odp.c
@@ -1797,9 +1797,7 @@ static bool init_prefetch_work(struct ib_pd *pd,
                work->frags[i].mr =
                        get_prefetchable_mr(pd, advice, sg_list[i].lkey);
                if (!work->frags[i].mr) {
-                       work->num_sge = i - 1;
-                       if (i)
-                               destroy_prefetch_work(work);
+                       work->num_sge = i;
                        return false;
                }
 
@@ -1865,6 +1863,7 @@ int mlx5_ib_advise_mr_prefetch(struct ib_pd *pd,
        srcu_key = srcu_read_lock(&dev->odp_srcu);
        if (!init_prefetch_work(pd, advice, pf_flags, work, sg_list, num_sge)) {
                srcu_read_unlock(&dev->odp_srcu, srcu_key);
+               destroy_prefetch_work(work);
                return -EINVAL;
        }
        queue_work(system_unbound_wq, &work->work);