UAS: fix deadlock in error handling and PM flushing work (f6cc6093) · Commits · 戴 / test

drivers/usb/storage/uas.c

+40 −3

Original line number	Diff line number	Diff line
		@@ -81,6 +81,19 @@ static void uas_free_streams(struct uas_dev_info *devinfo);
		static void uas_log_cmd_state(struct scsi_cmnd cmnd, const char prefix,
		int status);

		/*
		* This driver needs its own workqueue, as we need to control memory allocation.
		*
		* In the course of error handling and power management uas_wait_for_pending_cmnds()
		* needs to flush pending work items. In these contexts we cannot allocate memory
		* by doing block IO as we would deadlock. For the same reason we cannot wait
		* for anything allocating memory not heeding these constraints.
		*
		* So we have to control all work items that can be on the workqueue we flush.
		* Hence we cannot share a queue and need our own.
		*/
		static struct workqueue_struct *workqueue;

		static void uas_do_work(struct work_struct *work)
		{
		struct uas_dev_info *devinfo =
		@@ -109,7 +122,7 @@ static void uas_do_work(struct work_struct *work)
		if (!err)
		cmdinfo->state &= ~IS_IN_WORK_LIST;
		else
		schedule_work(&devinfo->work);
		queue_work(workqueue, &devinfo->work);
		}
		out:
		spin_unlock_irqrestore(&devinfo->lock, flags);
		@@ -134,7 +147,7 @@ static void uas_add_work(struct uas_cmd_info *cmdinfo)

		lockdep_assert_held(&devinfo->lock);
		cmdinfo->state \|= IS_IN_WORK_LIST;
		schedule_work(&devinfo->work);
		queue_work(workqueue, &devinfo->work);
		}

		static void uas_zap_pending(struct uas_dev_info *devinfo, int result)
		@@ -1229,7 +1242,31 @@ static struct usb_driver uas_driver = {
		.id_table = uas_usb_ids,
		};

		module_usb_driver(uas_driver);
		static int __init uas_init(void)
		{
		int rv;

		workqueue = alloc_workqueue("uas", WQ_MEM_RECLAIM, 0);
		if (!workqueue)
		return -ENOMEM;

		rv = usb_register(&uas_driver);
		if (rv) {
		destroy_workqueue(workqueue);
		return -ENOMEM;
		}

		return 0;
		}

		static void __exit uas_exit(void)
		{
		usb_deregister(&uas_driver);
		destroy_workqueue(workqueue);
		}

		module_init(uas_init);
		module_exit(uas_exit);

		MODULE_LICENSE("GPL");
		MODULE_IMPORT_NS(USB_STORAGE);

Admin message