[PATCH] USB: Limiting of resource use in skeleton driver (ff906518) · Commits · 戴 / test

drivers/usb/usb-skeleton.c

+18 −7

Original line number	Diff line number	Diff line
		@@ -39,10 +39,15 @@ MODULE_DEVICE_TABLE (usb, skel_table);
		/* Get a minor range for your devices from the usb maintainer */
		#define USB_SKEL_MINOR_BASE 192

		/* our private defines. if this grows any larger, use your own .h file */
		#define MAX_TRANSFER ( PAGE_SIZE - 512 )
		#define WRITES_IN_FLIGHT 8

		/* Structure to hold all of our device specific stuff */
		struct usb_skel {
		struct usb_device * udev; /* the usb device for this device */
		struct usb_interface * interface; /* the interface for this device */
		struct semaphore limit_sem; /* limiting the number of writes in progress */
		unsigned char * bulk_in_buffer; /* the buffer to receive data */
		size_t bulk_in_size; /* the size of the receive buffer */
		__u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */
		@@ -152,6 +157,7 @@ static void skel_write_bulk_callback(struct urb urb, struct pt_regs regs)
		/* free up our allocated buffer */
		usb_buffer_free(urb->dev, urb->transfer_buffer_length,
		urb->transfer_buffer, urb->transfer_dma);
		up(&dev->limit_sem);
		}

		static ssize_t skel_write(struct file file, const char user_buffer, size_t count, loff_t *ppos)
		@@ -160,6 +166,7 @@ static ssize_t skel_write(struct file file, const char user_buffer, size_t cou
		int retval = 0;
		struct urb *urb = NULL;
		char *buf = NULL;
		size_t writesize = max(count, MAX_TRANSFER);

		dev = (struct usb_skel *)file->private_data;

		@@ -167,6 +174,9 @@ static ssize_t skel_write(struct file file, const char user_buffer, size_t cou
		if (count == 0)
		goto exit;

		/* limit the number of URBs in flight to stop a user from using up all RAM */
		down (&dev->limit_sem);

		/* create a urb, and a buffer for it, and copy the data to the urb */
		urb = usb_alloc_urb(0, GFP_KERNEL);
		if (!urb) {
		@@ -174,13 +184,13 @@ static ssize_t skel_write(struct file file, const char user_buffer, size_t cou
		goto error;
		}

		buf = usb_buffer_alloc(dev->udev, count, GFP_KERNEL, &urb->transfer_dma);
		buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);
		if (!buf) {
		retval = -ENOMEM;
		goto error;
		}

		if (copy_from_user(buf, user_buffer, count)) {
		if (copy_from_user(buf, user_buffer, writesize)) {
		retval = -EFAULT;
		goto error;
		}
		@@ -188,7 +198,7 @@ static ssize_t skel_write(struct file file, const char user_buffer, size_t cou
		/* initialize the urb properly */
		usb_fill_bulk_urb(urb, dev->udev,
		usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
		buf, count, skel_write_bulk_callback, dev);
		buf, writesize, skel_write_bulk_callback, dev);
		urb->transfer_flags \|= URB_NO_TRANSFER_DMA_MAP;

		/* send the data out the bulk port */
		@@ -202,11 +212,12 @@ static ssize_t skel_write(struct file file, const char user_buffer, size_t cou
		usb_free_urb(urb);

		exit:
		return count;
		return writesize;

		error:
		usb_buffer_free(dev->udev, count, buf, urb->transfer_dma);
		usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
		usb_free_urb(urb);
		up(&dev->limit_sem);
		return retval;
		}

		@@ -238,13 +249,13 @@ static int skel_probe(struct usb_interface *interface, const struct usb_device_i
		int retval = -ENOMEM;

		/* allocate memory for our device state and initialize it */
		dev = kmalloc(sizeof(*dev), GFP_KERNEL);
		dev = kzalloc(sizeof(*dev), GFP_KERNEL);
		if (dev == NULL) {
		err("Out of memory");
		goto error;
		}
		memset(dev, 0x00, sizeof(*dev));
		kref_init(&dev->kref);
		sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);

		dev->udev = usb_get_dev(interface_to_usbdev(interface));
		dev->interface = interface;

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