USB: usb-skeleton: usb anchor to implement flush
This patch set introduces usb_anchor and uses it to implement all modern APIs in the skeleton driver. - proper error reporting in the skeleton driver - implementation of flush() Signed-off-by: Oliver Neukum <oneukum@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Oliver Neukum
Greg Kroah-Hartman
parent
51a2f077c4
commit
403dfb58c3
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@ -51,16 +51,20 @@ struct usb_skel {
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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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struct usb_anchor submitted; /* in case we need to retract our submissions */
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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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__u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */
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__u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */
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int errors; /* the last request tanked */
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spinlock_t err_lock; /* lock for errors */
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struct kref kref;
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struct mutex io_mutex; /* synchronize I/O with disconnect */
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};
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#define to_skel_dev(d) container_of(d, struct usb_skel, kref)
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static struct usb_driver skel_driver;
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static void skel_draw_down(struct usb_skel *dev);
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static void skel_delete(struct kref *kref)
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{
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@ -130,6 +134,30 @@ static int skel_release(struct inode *inode, struct file *file)
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return 0;
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}
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static int skel_flush(struct file *file, fl_owner_t id)
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{
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struct usb_skel *dev;
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int res;
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dev = (struct usb_skel *)file->private_data;
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if (dev == NULL)
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return -ENODEV;
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/* wait for io to stop */
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mutex_lock(&dev->io_mutex);
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skel_draw_down(dev);
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/* read out errors, leave subsequent opens a clean slate */
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spin_lock_irq(&dev->err_lock);
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res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
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dev->errors = 0;
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spin_unlock_irq(&dev->err_lock);
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mutex_unlock(&dev->io_mutex);
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return res;
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}
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static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos)
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{
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struct usb_skel *dev;
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@ -171,12 +199,16 @@ static void skel_write_bulk_callback(struct urb *urb)
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dev = (struct usb_skel *)urb->context;
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/* sync/async unlink faults aren't errors */
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if (urb->status &&
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!(urb->status == -ENOENT ||
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urb->status == -ECONNRESET ||
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urb->status == -ESHUTDOWN)) {
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err("%s - nonzero write bulk status received: %d",
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__FUNCTION__, urb->status);
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if (urb->status) {
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if(!(urb->status == -ENOENT ||
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urb->status == -ECONNRESET ||
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urb->status == -ESHUTDOWN))
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err("%s - nonzero write bulk status received: %d",
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__FUNCTION__, urb->status);
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spin_lock(&dev->err_lock);
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dev->errors = urb->status;
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spin_unlock(&dev->err_lock);
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}
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/* free up our allocated buffer */
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@ -205,6 +237,17 @@ 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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spin_lock_irq(&dev->err_lock);
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if ((retval = dev->errors) < 0) {
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/* any error is reported once */
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dev->errors = 0;
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/* to preserve notifications about reset */
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retval = (retval == -EPIPE) ? retval : -EIO;
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}
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spin_unlock_irq(&dev->err_lock);
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if (retval < 0)
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goto error;
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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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@ -236,13 +279,14 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou
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usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
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buf, writesize, skel_write_bulk_callback, dev);
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urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
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usb_anchor_urb(urb, &dev->submitted);
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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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goto error_unanchor;
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}
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/* release our reference to this urb, the USB core will eventually free it entirely */
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@ -251,6 +295,8 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou
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return writesize;
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error_unanchor:
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usb_unanchor_urb(urb);
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error:
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if (urb) {
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usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
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@ -268,6 +314,7 @@ static const struct file_operations skel_fops = {
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.write = skel_write,
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.open = skel_open,
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.release = skel_release,
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.flush = skel_flush,
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};
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/*
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@ -298,6 +345,8 @@ static int skel_probe(struct usb_interface *interface, const struct usb_device_i
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kref_init(&dev->kref);
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sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
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mutex_init(&dev->io_mutex);
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spin_lock_init(&dev->err_lock);
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init_usb_anchor(&dev->submitted);
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dev->udev = usb_get_dev(interface_to_usbdev(interface));
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dev->interface = interface;
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@ -377,6 +426,15 @@ static void skel_disconnect(struct usb_interface *interface)
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info("USB Skeleton #%d now disconnected", minor);
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}
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static void skel_draw_down(struct usb_skel *dev)
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{
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int time;
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time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
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if (!time)
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usb_kill_anchored_urbs(&dev->submitted);
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}
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static struct usb_driver skel_driver = {
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.name = "skeleton",
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.probe = skel_probe,
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