[PATCH 4.19 03/79] RDMA/restrack: Release task struct which was hold by CM_ID object

Greg Kroah-Hartman
2019-09-19T22:12:59Z

From: Leon Romanovsky <leonro@mellanox.com>

commit ed7a01fd3fd77f40b4ef2562b966a5decd8928d2 upstream.

Tracking CM_ID resource is performed in two stages: creation of cm_id
and connecting it to the cma_dev. It is needed because rdma-cm protocol
exports two separate user-visible calls rdma_create_id and rdma_accept.

At the time of CM_ID creation, the real owner of that object is unknown
yet and we need to grab task_struct. This task_struct is released or
reassigned in attach phase later on. but call to rdma_destroy_id left
this task_struct unreleased.

Such separation is unique to CM_ID and other restrack objects initialize
in one shot. It means that it is safe to use "res->valid" check to catch
unfinished CM_ID flow and release task_struct for that object.

Fixes: 00313983cda6 ("RDMA/nldev: provide detailed CM_ID information")
Reported-by: Artemy Kovalyov <artemyko@mellanox.com>
Reviewed-by: Artemy Kovalyov <artemyko@mellanox.com>
Reviewed-by: Yossi Itigin <yosefe@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Cc: Håkon Bugge <haakon.bugge@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/infiniband/core/cma.c | 7 +++----
drivers/infiniband/core/restrack.c | 6 ++++--
2 files changed, 7 insertions(+), 6 deletions(-)

--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -1723,8 +1723,8 @@ void rdma_destroy_id(struct rdma_cm_id *
mutex_lock(&id_priv->handler_mutex);
mutex_unlock(&id_priv->handler_mutex);

+ rdma_restrack_del(&id_priv->res);
if (id_priv->cma_dev) {
- rdma_restrack_del(&id_priv->res);
if (rdma_cap_ib_cm(id_priv->id.device, 1)) {
if (id_priv->cm_id.ib)
ib_destroy_cm_id(id_priv->cm_id.ib);
@@ -3463,10 +3463,9 @@ int rdma_bind_addr(struct rdma_cm_id *id

return 0;
err2:
- if (id_priv->cma_dev) {
- rdma_restrack_del(&id_priv->res);
+ rdma_restrack_del(&id_priv->res);
+ if (id_priv->cma_dev)
cma_release_dev(id_priv);
- }
err1:
cma_comp_exch(id_priv, RDMA_CM_ADDR_BOUND, RDMA_CM_IDLE);
return ret;
--- a/drivers/infiniband/core/restrack.c
+++ b/drivers/infiniband/core/restrack.c
@@ -209,7 +209,7 @@ void rdma_restrack_del(struct rdma_restr
struct ib_device *dev;

if (!res->valid)
- return;
+ goto out;

dev = res_to_dev(res);
if (!dev)
@@ -222,8 +222,10 @@ void rdma_restrack_del(struct rdma_restr
down_write(&dev->res.rwsem);
hash_del(&res->node);
res->valid = false;
+ up_write(&dev->res.rwsem);
+
+out:
if (res->task)
put_task_struct(res->task);
- up_write(&dev->res.rwsem);
}
EXPORT_SYMBOL(rdma_restrack_del);