RDMA/iser: Fix possible mr leak on device removal event

When the rdma device is removed, we must cleanup all
the rdma resources within the DEVICE_REMOVAL event
handler to let the device teardown gracefully. When
this happens with live I/O, some memory regions are
occupied. Thus, track them too and dereg all the mr's.

We are safe with mr access by iscsi_iser_cleanup_task.

Reported-by: Raju Rangoju <[e-mail]>
Signed-off-by: Sagi Grimberg <[e-mail]>
Reviewed-by: Max Gurtovoy <[e-mail]>
Reviewed-by: Max Gurtovoy <[e-mail]>
Signed-off-by: Doug Ledford <[e-mail]>

drivers/infiniband/ulp/iser/iscsi_iser.h

···
 	struct list_head		  list;
 	struct iser_reg_resources	  rsc;
 	struct iser_pi_context		 *pi_ctx;
+	struct list_head                  all_list;
 };
 
 /**
···
 	struct list_head        list;
 	spinlock_t              lock;
 	int                     size;
+	struct list_head        all_list;
 };
 
 /**

drivers/infiniband/ulp/iser/iser_verbs.c

···
 	int i, ret;
 
 	INIT_LIST_HEAD(&fr_pool->list);
+	INIT_LIST_HEAD(&fr_pool->all_list);
 	spin_lock_init(&fr_pool->lock);
 	fr_pool->size = 0;
 	for (i = 0; i < cmds_max; i++) {
···
 		}
 
 		list_add_tail(&desc->list, &fr_pool->list);
+		list_add_tail(&desc->all_list, &fr_pool->all_list);
 		fr_pool->size++;
 	}
 
···
 	struct iser_fr_desc *desc, *tmp;
 	int i = 0;
 
-	if (list_empty(&fr_pool->list))
+	if (list_empty(&fr_pool->all_list))
 		return;
 
 	iser_info("freeing conn %p fr pool\n", ib_conn);
 
-	list_for_each_entry_safe(desc, tmp, &fr_pool->list, list) {
-		list_del(&desc->list);
+	list_for_each_entry_safe(desc, tmp, &fr_pool->all_list, all_list) {
+		list_del(&desc->all_list);
 		iser_free_reg_res(&desc->rsc);
 		if (desc->pi_ctx)
 			iser_free_pi_ctx(desc->pi_ctx);