diff options
Diffstat (limited to 'drivers/usb/usb-skeleton.c')
| -rw-r--r-- | drivers/usb/usb-skeleton.c | 151 |
1 files changed, 126 insertions, 25 deletions
diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c index 8432bf1..8de11de 100644 --- a/drivers/usb/usb-skeleton.c +++ b/drivers/usb/usb-skeleton.c @@ -34,9 +34,6 @@ static struct usb_device_id skel_table [] = { }; MODULE_DEVICE_TABLE(usb, skel_table); -/* to prevent a race between open and disconnect */ -static DEFINE_MUTEX(skel_open_lock); - /* Get a minor range for your devices from the usb maintainer */ #define USB_SKEL_MINOR_BASE 192 @@ -54,16 +51,21 @@ 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 */ + struct usb_anchor submitted; /* in case we need to retract our submissions */ 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 */ __u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */ + int errors; /* the last request tanked */ + int open_count; /* count the number of openers */ + spinlock_t err_lock; /* lock for errors */ struct kref kref; struct mutex io_mutex; /* synchronize I/O with disconnect */ }; #define to_skel_dev(d) container_of(d, struct usb_skel, kref) static struct usb_driver skel_driver; +static void skel_draw_down(struct usb_skel *dev); static void skel_delete(struct kref *kref) { @@ -83,10 +85,8 @@ static int skel_open(struct inode *inode, struct file *file) subminor = iminor(inode); - mutex_lock(&skel_open_lock); interface = usb_find_interface(&skel_driver, subminor); if (!interface) { - mutex_unlock(&skel_open_lock); err ("%s - error, can't find device for minor %d", __FUNCTION__, subminor); retval = -ENODEV; @@ -95,22 +95,33 @@ static int skel_open(struct inode *inode, struct file *file) dev = usb_get_intfdata(interface); if (!dev) { - mutex_unlock(&skel_open_lock); retval = -ENODEV; goto exit; } /* increment our usage count for the device */ kref_get(&dev->kref); - /* now we can drop the lock */ - mutex_unlock(&skel_open_lock); - /* prevent the device from being autosuspended */ - retval = usb_autopm_get_interface(interface); - if (retval) { + /* lock the device to allow correctly handling errors + * in resumption */ + mutex_lock(&dev->io_mutex); + + if (!dev->open_count++) { + retval = usb_autopm_get_interface(interface); + if (retval) { + dev->open_count--; + mutex_unlock(&dev->io_mutex); + kref_put(&dev->kref, skel_delete); + goto exit; + } + } /* else { //uncomment this block if you want exclusive open + retval = -EBUSY; + dev->open_count--; + mutex_unlock(&dev->io_mutex); kref_put(&dev->kref, skel_delete); goto exit; - } + } */ + /* prevent the device from being autosuspended */ /* save our object in the file's private structure */ file->private_data = dev; @@ -129,7 +140,7 @@ static int skel_release(struct inode *inode, struct file *file) /* allow the device to be autosuspended */ mutex_lock(&dev->io_mutex); - if (dev->interface) + if (!--dev->open_count && dev->interface) usb_autopm_put_interface(dev->interface); mutex_unlock(&dev->io_mutex); @@ -138,6 +149,30 @@ static int skel_release(struct inode *inode, struct file *file) return 0; } +static int skel_flush(struct file *file, fl_owner_t id) +{ + struct usb_skel *dev; + int res; + + dev = (struct usb_skel *)file->private_data; + if (dev == NULL) + return -ENODEV; + + /* wait for io to stop */ + mutex_lock(&dev->io_mutex); + skel_draw_down(dev); + + /* read out errors, leave subsequent opens a clean slate */ + spin_lock_irq(&dev->err_lock); + res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0; + dev->errors = 0; + spin_unlock_irq(&dev->err_lock); + + mutex_unlock(&dev->io_mutex); + + return res; +} + static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos) { struct usb_skel *dev; @@ -179,12 +214,16 @@ static void skel_write_bulk_callback(struct urb *urb) dev = (struct usb_skel *)urb->context; /* sync/async unlink faults aren't errors */ - if (urb->status && - !(urb->status == -ENOENT || - urb->status == -ECONNRESET || - urb->status == -ESHUTDOWN)) { - err("%s - nonzero write bulk status received: %d", - __FUNCTION__, urb->status); + if (urb->status) { + if(!(urb->status == -ENOENT || + urb->status == -ECONNRESET || + urb->status == -ESHUTDOWN)) + err("%s - nonzero write bulk status received: %d", + __FUNCTION__, urb->status); + + spin_lock(&dev->err_lock); + dev->errors = urb->status; + spin_unlock(&dev->err_lock); } /* free up our allocated buffer */ @@ -213,6 +252,17 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou goto exit; } + spin_lock_irq(&dev->err_lock); + if ((retval = dev->errors) < 0) { + /* any error is reported once */ + dev->errors = 0; + /* to preserve notifications about reset */ + retval = (retval == -EPIPE) ? retval : -EIO; + } + spin_unlock_irq(&dev->err_lock); + if (retval < 0) + goto error; + /* create a urb, and a buffer for it, and copy the data to the urb */ urb = usb_alloc_urb(0, GFP_KERNEL); if (!urb) { @@ -244,13 +294,14 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr), buf, writesize, skel_write_bulk_callback, dev); urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP; + usb_anchor_urb(urb, &dev->submitted); /* send the data out the bulk port */ retval = usb_submit_urb(urb, GFP_KERNEL); mutex_unlock(&dev->io_mutex); if (retval) { err("%s - failed submitting write urb, error %d", __FUNCTION__, retval); - goto error; + goto error_unanchor; } /* release our reference to this urb, the USB core will eventually free it entirely */ @@ -259,6 +310,8 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou return writesize; +error_unanchor: + usb_unanchor_urb(urb); error: if (urb) { usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma); @@ -276,6 +329,7 @@ static const struct file_operations skel_fops = { .write = skel_write, .open = skel_open, .release = skel_release, + .flush = skel_flush, }; /* @@ -306,6 +360,8 @@ static int skel_probe(struct usb_interface *interface, const struct usb_device_i kref_init(&dev->kref); sema_init(&dev->limit_sem, WRITES_IN_FLIGHT); mutex_init(&dev->io_mutex); + spin_lock_init(&dev->err_lock); + init_usb_anchor(&dev->submitted); dev->udev = usb_get_dev(interface_to_usbdev(interface)); dev->interface = interface; @@ -368,22 +424,18 @@ static void skel_disconnect(struct usb_interface *interface) struct usb_skel *dev; int minor = interface->minor; - /* prevent skel_open() from racing skel_disconnect() */ - mutex_lock(&skel_open_lock); - dev = usb_get_intfdata(interface); usb_set_intfdata(interface, NULL); /* give back our minor */ usb_deregister_dev(interface, &skel_class); - mutex_unlock(&skel_open_lock); /* prevent more I/O from starting */ mutex_lock(&dev->io_mutex); dev->interface = NULL; mutex_unlock(&dev->io_mutex); - + usb_kill_anchored_urbs(&dev->submitted); /* decrement our usage count */ kref_put(&dev->kref, skel_delete); @@ -391,10 +443,59 @@ static void skel_disconnect(struct usb_interface *interface) info("USB Skeleton #%d now disconnected", minor); } +static void skel_draw_down(struct usb_skel *dev) +{ + int time; + + time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000); + if (!time) + usb_kill_anchored_urbs(&dev->submitted); +} + +static int skel_suspend(struct usb_interface *intf, pm_message_t message) +{ + struct usb_skel *dev = usb_get_intfdata(intf); + + if (!dev) + return 0; + skel_draw_down(dev); + return 0; +} + +static int skel_resume (struct usb_interface *intf) +{ + return 0; +} + +static int skel_pre_reset(struct usb_interface *intf) +{ + struct usb_skel *dev = usb_get_intfdata(intf); + + mutex_lock(&dev->io_mutex); + skel_draw_down(dev); + + return 0; +} + +static int skel_post_reset(struct usb_interface *intf) +{ + struct usb_skel *dev = usb_get_intfdata(intf); + + /* we are sure no URBs are active - no locking needed */ + dev->errors = -EPIPE; + mutex_unlock(&dev->io_mutex); + + return 0; +} + static struct usb_driver skel_driver = { .name = "skeleton", .probe = skel_probe, .disconnect = skel_disconnect, + .suspend = skel_suspend, + .resume = skel_resume, + .pre_reset = skel_pre_reset, + .post_reset = skel_post_reset, .id_table = skel_table, .supports_autosuspend = 1, }; |