USB: fix skeleton driver
compilation of the skeleton driver is currently broken. It doesn't compile. So while I am it: - fix typo - add comments to answer common questions - actually allow autosuspend in the driver struct - increase paralellism by restricting code under locks Signed-off-by: Oliver Neukum <oneukum@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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@ -40,12 +40,16 @@ MODULE_DEVICE_TABLE(usb, skel_table);
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/* our private defines. if this grows any larger, use your own .h file */
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#define MAX_TRANSFER (PAGE_SIZE - 512)
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/* MAX_TRANSFER is chosen so that the VM is not stressed by
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allocations > PAGE_SIZE and the number of packets in a page
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is an integer 512 is the largest possible packet on EHCI */
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#define WRITES_IN_FLIGHT 8
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/* arbitrarily chosen */
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/* Structure to hold all of our device specific stuff */
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struct usb_skel {
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struct usb_device *dev; /* the usb device for this device */
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struct usb_interface *interface; /* the interface for this device */
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struct usb_device *udev; /* the usb device for this device */
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struct usb_interface *interface; /* the interface for this device */
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struct semaphore limit_sem; /* limiting the number of writes in progress */
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unsigned char *bulk_in_buffer; /* the buffer to receive data */
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size_t bulk_in_size; /* the size of the receive buffer */
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@ -201,12 +205,6 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou
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goto exit;
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}
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mutex_lock(&dev->io_mutex);
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if (!dev->interface) { /* disconnect() was called */
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retval = -ENODEV;
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goto error;
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}
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/* create a urb, and a buffer for it, and copy the data to the urb */
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urb = usb_alloc_urb(0, GFP_KERNEL);
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if (!urb) {
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@ -225,6 +223,14 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou
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goto error;
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}
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/* this lock makes sure we don't submit URBs to gone devices */
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mutex_lock(&dev->io_mutex);
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if (!dev->interface) { /* disconnect() was called */
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mutex_unlock(&dev->io_mutex);
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retval = -ENODEV;
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goto error;
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}
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/* initialize the urb properly */
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usb_fill_bulk_urb(urb, dev->udev,
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usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
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@ -233,6 +239,7 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou
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/* send the data out the bulk port */
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retval = usb_submit_urb(urb, GFP_KERNEL);
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mutex_unlock(&dev->io_mutex);
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if (retval) {
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err("%s - failed submitting write urb, error %d", __FUNCTION__, retval);
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goto error;
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@ -241,7 +248,7 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou
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/* release our reference to this urb, the USB core will eventually free it entirely */
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usb_free_urb(urb);
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mutex_unlock(&dev->io_mutex);
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return writesize;
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error:
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@ -249,7 +256,6 @@ error:
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usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
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usb_free_urb(urb);
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}
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mutex_unlock(&dev->io_mutex);
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up(&dev->limit_sem);
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exit:
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@ -344,6 +350,7 @@ static int skel_probe(struct usb_interface *interface, const struct usb_device_i
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error:
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if (dev)
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/* this frees allocated memory */
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kref_put(&dev->kref, skel_delete);
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return retval;
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}
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@ -361,13 +368,14 @@ static void skel_disconnect(struct usb_interface *interface)
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/* give back our minor */
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usb_deregister_dev(interface, &skel_class);
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unlock_kernel();
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/* prevent more I/O from starting */
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mutex_lock(&dev->io_mutex);
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dev->interface = NULL;
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mutex_unlock(&dev->io_mutex);
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unlock_kernel();
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/* decrement our usage count */
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kref_put(&dev->kref, skel_delete);
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@ -380,6 +388,7 @@ static struct usb_driver skel_driver = {
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.probe = skel_probe,
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.disconnect = skel_disconnect,
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.id_table = skel_table,
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.supports_autosuspend = 1,
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};
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static int __init usb_skel_init(void)
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