RDMA/restrack: Release task struct which was hold by CM_ID object

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>

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index f117b75..f98ddb5 100644 (file)
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -1815,8 +1815,8 @@ void rdma_destroy_id(struct rdma_cm_id *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);
@@ -3542,10 +3542,9 @@ int rdma_bind_addr(struct rdma_cm_id *id, struct sockaddr *addr)
 
        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;

diff --git a/drivers/infiniband/core/restrack.c b/drivers/infiniband/core/restrack.c
index 035af56..16b5f99 100644 (file)
--- a/drivers/infiniband/core/restrack.c
+++ b/drivers/infiniband/core/restrack.c
@@ -223,7 +223,7 @@ void rdma_restrack_del(struct rdma_restrack_entry *res)
        struct ib_device *dev;
 
        if (!res->valid)
-               return;
+               goto out;
 
        dev = res_to_dev(res);
        if (!dev)
@@ -236,8 +236,10 @@ void rdma_restrack_del(struct rdma_restrack_entry *res)
        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);