dmaengine: idxd: add per DSA wq workqueue for processing cr faults

Add a workqueue for user submitted completion record fault processing.
The workqueue creation and destruction lifetime will be tied to the user
sub-driver since it will only be used when the wq is a user type.

Tested-by: Tony Zhu <tony.zhu@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Co-developed-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: https://lore.kernel.org/r/20230407203143.2189681-7-fenghua.yu@intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/idxd/cdev.c

@@ -330,6 +330,13 @@ static int idxd_user_drv_probe(struct idxd_dev *idxd_dev)
 	}
 
 	mutex_lock(&wq->wq_lock);
+
+	wq->wq = create_workqueue(dev_name(wq_confdev(wq)));
+	if (!wq->wq) {
+		rc = -ENOMEM;
+		goto wq_err;
+	}
+
 	wq->type = IDXD_WQT_USER;
 	rc = drv_enable_wq(wq);
 	if (rc < 0)
@@ -348,7 +355,9 @@ static int idxd_user_drv_probe(struct idxd_dev *idxd_dev)
 err_cdev:
 	drv_disable_wq(wq);
 err:
+	destroy_workqueue(wq->wq);
 	wq->type = IDXD_WQT_NONE;
+wq_err:
 	mutex_unlock(&wq->wq_lock);
 	return rc;
 }
@@ -361,6 +370,8 @@ static void idxd_user_drv_remove(struct idxd_dev *idxd_dev)
 	idxd_wq_del_cdev(wq);
 	drv_disable_wq(wq);
 	wq->type = IDXD_WQT_NONE;
+	destroy_workqueue(wq->wq);
+	wq->wq = NULL;
 	mutex_unlock(&wq->wq_lock);
 }
 

drivers/dma/idxd/idxd.h

@@ -185,6 +185,7 @@ struct idxd_wq {
 	struct idxd_dev idxd_dev;
 	struct idxd_cdev *idxd_cdev;
 	struct wait_queue_head err_queue;
+	struct workqueue_struct *wq;
 	struct idxd_device *idxd;
 	int id;
 	struct idxd_irq_entry ie;