IB/isert: Properly release resources on DEVICE_REMOVAL

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@chelsio.com>
Acked-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Doug Ledford <dledford@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/infiniband/ulp/isert/ib_isert.h b/drivers/infiniband/ulp/isert/ib_isert.h
index fc791efe3a10..c02ada57d7f5 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