[PATCH 1/1] IB/isert: Properly release resources on RDMA_CM_EVENT_DEVICE_REMOVAL

Raju Rangoju
2016-08-29T11:45:49Z

When the low level driver exercises the hot unplug they would call
rdma_cm cma_remove_one which would fire DEVICE_REMOVAL event to all cma
consumers. Now, if consumer doesn't make sure they destroy all IB
objects created on that IB device instance prior to finalizing all
processing of DEVICE_REMOVAL callback, rdma_cm will let the lld to
de-register with IB core and destroy the IB device instance. And if the
consumer calls (say) ib_dereg_mr(), it will crash since that dev object
is NULL.

In the current implementation, iser-target just initiates the cleanup
and returns from DEVICE_REMOVAL callback. This deferred work creates a
race between iser-target cleaning IB objects(say MR) and lld destroying
IB device instance.

This patch includes the following fixes
-> make sure that consumer frees all IB objects associated with device
instance
-> return non-zero from the callback to destroy the rdma_cm id

Signed-off-by: Raju Rangoju <rajur-ut6Up61K2wZBDgjK7y7TUQ@public.gmane.org>
Acked-by: Sagi Grimberg <sagi-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>
---
drivers/infiniband/ulp/isert/ib_isert.c | 23 ++++++++++++++++++++---
drivers/infiniband/ulp/isert/ib_isert.h | 2 ++
2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
index 7914c14..cae9bbc 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -403,6 +403,7 @@ isert_init_conn(struct isert_conn *isert_conn)
INIT_LIST_HEAD(&isert_conn->node);
init_completion(&isert_conn->login_comp);
init_completion(&isert_conn->login_req_comp);
+ init_waitqueue_head(&isert_conn->rem_wait);
kref_init(&isert_conn->kref);
mutex_init(&isert_conn->mutex);
INIT_WORK(&isert_conn->release_work, isert_release_work);
@@ -578,7 +579,8 @@ isert_connect_release(struct isert_conn *isert_conn)
BUG_ON(!device);

isert_free_rx_descriptors(isert_conn);
- if (isert_conn->cm_id)
+ if (isert_conn->cm_id &&
+ !isert_conn->dev_removed)
rdma_destroy_id(isert_conn->cm_id);

if (isert_conn->qp) {
@@ -593,7 +595,10 @@ isert_connect_release(struct isert_conn *isert_conn)

isert_device_put(device);

- kfree(isert_conn);
+ if (isert_conn->dev_removed)
+ wake_up_interruptible(&isert_conn->rem_wait);
+ else
+ kfree(isert_conn);
}

static void
@@ -753,6 +758,7 @@ static int
isert_cma_handler(struct rdma_cm_id *cma_id, struct rdma_cm_event *event)
{
struct isert_np *isert_np = cma_id->context;
+ struct isert_conn *isert_conn;
int ret = 0;

isert_info("%s (%d): status %d id %p np %p\n",
@@ -773,10 +779,21 @@ isert_cma_handler(struct rdma_cm_id *cma_id, struct rdma_cm_event *event)
break;
case RDMA_CM_EVENT_ADDR_CHANGE: /* FALLTHRU */
case RDMA_CM_EVENT_DISCONNECTED: /* FALLTHRU */
- case RDMA_CM_EVENT_DEVICE_REMOVAL: /* FALLTHRU */
case RDMA_CM_EVENT_TIMEWAIT_EXIT: /* FALLTHRU */
ret = isert_disconnected_handler(cma_id, event->event);
break;
+ case RDMA_CM_EVENT_DEVICE_REMOVAL:
+ isert_conn = cma_id->qp->qp_context;
+ isert_conn->dev_removed = true;
+ isert_disconnected_handler(cma_id, event->event);
+ wait_event_interruptible(isert_conn->rem_wait,
+ isert_conn->state == ISER_CONN_DOWN);
+ kfree(isert_conn);
+ /*
+ * return non-zero from the callback to destroy
+ * the rdma cm id
+ */
+ return 1;
case RDMA_CM_EVENT_REJECTED: /* FALLTHRU */
case RDMA_CM_EVENT_UNREACHABLE: /* FALLTHRU */
case RDMA_CM_EVENT_CONNECT_ERROR:
diff --git a/drivers/infiniband/ulp/isert/ib_isert.h b/drivers/infiniband/ulp/isert/ib_isert.h
index fc791ef..c02ada5 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.h
+++ b/drivers/infiniband/ulp/isert/ib_isert.h
@@ -158,6 +158,8 @@ struct isert_conn {
struct work_struct release_work;
bool logout_posted;
bool snd_w_inv;
+ wait_queue_head_t rem_wait;
+ bool dev_removed;
};

#define ISERT_MAX_CQ 64
--
2.8.3