X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=drivers%2Fusb%2Fusb-skeleton.c;h=b1e579c5c97cbb90bc19be3619d41aaee1f8e6f4;hb=471452104b8520337ae2fb48c4e61cd4896e025d;hp=1b51d3187a95c8d99c87de153de5afed4a9831ea;hpb=01d883d44a1ca8dc77486635d428cba63e7fdadf;p=safe%2Fjmp%2Flinux-2.6 diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c index 1b51d31..b1e579c 100644 --- a/drivers/usb/usb-skeleton.c +++ b/drivers/usb/usb-skeleton.c @@ -18,7 +18,7 @@ #include #include #include -#include +#include #include #include @@ -28,7 +28,7 @@ #define USB_SKEL_PRODUCT_ID 0xfff0 /* table of devices that work with this driver */ -static struct usb_device_id skel_table [] = { +static struct usb_device_id skel_table[] = { { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) }, { } /* Terminating entry */ }; @@ -40,28 +40,44 @@ MODULE_DEVICE_TABLE(usb, skel_table); /* our private defines. if this grows any larger, use your own .h file */ #define MAX_TRANSFER (PAGE_SIZE - 512) +/* MAX_TRANSFER is chosen so that the VM is not stressed by + allocations > PAGE_SIZE and the number of packets in a page + is an integer 512 is the largest possible packet on EHCI */ #define WRITES_IN_FLIGHT 8 +/* arbitrarily chosen */ /* Structure to hold all of our device specific stuff */ struct usb_skel { - struct usb_device *dev; /* the usb device for this device */ - struct usb_interface *interface; /* the interface for this device */ + 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 */ + struct urb *bulk_in_urb; /* the urb to read data with */ unsigned char *bulk_in_buffer; /* the buffer to receive data */ size_t bulk_in_size; /* the size of the receive buffer */ + size_t bulk_in_filled; /* number of bytes in the buffer */ + size_t bulk_in_copied; /* already copied to user space */ __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 */ + bool ongoing_read; /* a read is going on */ + bool processed_urb; /* indicates we haven't processed the urb */ + spinlock_t err_lock; /* lock for errors */ struct kref kref; struct mutex io_mutex; /* synchronize I/O with disconnect */ + struct completion bulk_in_completion; /* to wait for an ongoing read */ }; #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) { struct usb_skel *dev = to_skel_dev(kref); + usb_free_urb(dev->bulk_in_urb); usb_put_dev(dev->udev); kfree(dev->bulk_in_buffer); kfree(dev); @@ -78,8 +94,8 @@ static int skel_open(struct inode *inode, struct file *file) interface = usb_find_interface(&skel_driver, subminor); if (!interface) { - err ("%s - error, can't find device for minor %d", - __FUNCTION__, subminor); + err("%s - error, can't find device for minor %d", + __func__, subminor); retval = -ENODEV; goto exit; } @@ -90,16 +106,33 @@ static int skel_open(struct inode *inode, struct file *file) goto exit; } - /* prevent the device from being autosuspended */ - retval = usb_autopm_get_interface(interface); - if (retval) - goto exit; - /* increment our usage count for the device */ kref_get(&dev->kref); + /* 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; + mutex_unlock(&dev->io_mutex); exit: return retval; @@ -115,7 +148,7 @@ 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); @@ -124,53 +157,233 @@ static int skel_release(struct inode *inode, struct file *file) return 0; } -static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos) +static int skel_flush(struct file *file, fl_owner_t id) { struct usb_skel *dev; - int retval; - int bytes_read; + 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 void skel_read_bulk_callback(struct urb *urb) +{ + struct usb_skel *dev; + + dev = urb->context; + + spin_lock(&dev->err_lock); + /* sync/async unlink faults aren't errors */ + if (urb->status) { + if (!(urb->status == -ENOENT || + urb->status == -ECONNRESET || + urb->status == -ESHUTDOWN)) + err("%s - nonzero write bulk status received: %d", + __func__, urb->status); + + dev->errors = urb->status; + } else { + dev->bulk_in_filled = urb->actual_length; + } + dev->ongoing_read = 0; + spin_unlock(&dev->err_lock); + + complete(&dev->bulk_in_completion); +} + +static int skel_do_read_io(struct usb_skel *dev, size_t count) +{ + int rv; + + /* prepare a read */ + usb_fill_bulk_urb(dev->bulk_in_urb, + dev->udev, + usb_rcvbulkpipe(dev->udev, + dev->bulk_in_endpointAddr), + dev->bulk_in_buffer, + min(dev->bulk_in_size, count), + skel_read_bulk_callback, + dev); + /* tell everybody to leave the URB alone */ + spin_lock_irq(&dev->err_lock); + dev->ongoing_read = 1; + spin_unlock_irq(&dev->err_lock); + + /* do it */ + rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL); + if (rv < 0) { + err("%s - failed submitting read urb, error %d", + __func__, rv); + dev->bulk_in_filled = 0; + rv = (rv == -ENOMEM) ? rv : -EIO; + spin_lock_irq(&dev->err_lock); + dev->ongoing_read = 0; + spin_unlock_irq(&dev->err_lock); + } + + return rv; +} + +static ssize_t skel_read(struct file *file, char *buffer, size_t count, + loff_t *ppos) +{ + struct usb_skel *dev; + int rv; + bool ongoing_io; + + dev = (struct usb_skel *)file->private_data; + + /* if we cannot read at all, return EOF */ + if (!dev->bulk_in_urb || !count) + return 0; + + /* no concurrent readers */ + rv = mutex_lock_interruptible(&dev->io_mutex); + if (rv < 0) + return rv; + if (!dev->interface) { /* disconnect() was called */ - retval = -ENODEV; + rv = -ENODEV; goto exit; } - /* do a blocking bulk read to get data from the device */ - retval = usb_bulk_msg(dev->udev, - usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr), - dev->bulk_in_buffer, - min(dev->bulk_in_size, count), - &bytes_read, 10000); - - /* if the read was successful, copy the data to userspace */ - if (!retval) { - if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read)) - retval = -EFAULT; - else - retval = bytes_read; + /* if IO is under way, we must not touch things */ +retry: + spin_lock_irq(&dev->err_lock); + ongoing_io = dev->ongoing_read; + spin_unlock_irq(&dev->err_lock); + + if (ongoing_io) { + /* nonblocking IO shall not wait */ + if (file->f_flags & O_NONBLOCK) { + rv = -EAGAIN; + goto exit; + } + /* + * IO may take forever + * hence wait in an interruptible state + */ + rv = wait_for_completion_interruptible(&dev->bulk_in_completion); + if (rv < 0) + goto exit; + /* + * by waiting we also semiprocessed the urb + * we must finish now + */ + dev->bulk_in_copied = 0; + dev->processed_urb = 1; + } + + if (!dev->processed_urb) { + /* + * the URB hasn't been processed + * do it now + */ + wait_for_completion(&dev->bulk_in_completion); + dev->bulk_in_copied = 0; + dev->processed_urb = 1; } + /* errors must be reported */ + rv = dev->errors; + if (rv < 0) { + /* any error is reported once */ + dev->errors = 0; + /* to preserve notifications about reset */ + rv = (rv == -EPIPE) ? rv : -EIO; + /* no data to deliver */ + dev->bulk_in_filled = 0; + /* report it */ + goto exit; + } + + /* + * if the buffer is filled we may satisfy the read + * else we need to start IO + */ + + if (dev->bulk_in_filled) { + /* we had read data */ + size_t available = dev->bulk_in_filled - dev->bulk_in_copied; + size_t chunk = min(available, count); + + if (!available) { + /* + * all data has been used + * actual IO needs to be done + */ + rv = skel_do_read_io(dev, count); + if (rv < 0) + goto exit; + else + goto retry; + } + /* + * data is available + * chunk tells us how much shall be copied + */ + + if (copy_to_user(buffer, + dev->bulk_in_buffer + dev->bulk_in_copied, + chunk)) + rv = -EFAULT; + else + rv = chunk; + + dev->bulk_in_copied += chunk; + + /* + * if we are asked for more than we have, + * we start IO but don't wait + */ + if (available < count) + skel_do_read_io(dev, count - chunk); + } else { + /* no data in the buffer */ + rv = skel_do_read_io(dev, count); + if (rv < 0) + goto exit; + else if (!(file->f_flags & O_NONBLOCK)) + goto retry; + rv = -EAGAIN; + } exit: mutex_unlock(&dev->io_mutex); - return retval; + return rv; } -static void skel_write_bulk_callback(struct urb *urb, struct pt_regs *regs) +static void skel_write_bulk_callback(struct urb *urb) { struct usb_skel *dev; - dev = (struct usb_skel *)urb->context; + dev = 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", + __func__, urb->status); + + spin_lock(&dev->err_lock); + dev->errors = urb->status; + spin_unlock(&dev->err_lock); } /* free up our allocated buffer */ @@ -179,7 +392,8 @@ static void skel_write_bulk_callback(struct urb *urb, struct pt_regs *regs) up(&dev->limit_sem); } -static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos) +static ssize_t skel_write(struct file *file, const char *user_buffer, + size_t count, loff_t *ppos) { struct usb_skel *dev; int retval = 0; @@ -193,17 +407,33 @@ 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 */ - if (down_interruptible(&dev->limit_sem)) { - retval = -ERESTARTSYS; - goto exit; + /* + * limit the number of URBs in flight to stop a user from using up all + * RAM + */ + if (!(file->f_flags & O_NONBLOCK)) { + if (down_interruptible(&dev->limit_sem)) { + retval = -ERESTARTSYS; + goto exit; + } + } else { + if (down_trylock(&dev->limit_sem)) { + retval = -EAGAIN; + goto exit; + } } - mutex_lock(&dev->io_mutex); - if (!dev->interface) { /* disconnect() was called */ - retval = -ENODEV; - goto error; + spin_lock_irq(&dev->err_lock); + retval = dev->errors; + if (retval < 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); @@ -212,7 +442,8 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou goto error; } - buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma); + buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, + &urb->transfer_dma); if (!buf) { retval = -ENOMEM; goto error; @@ -223,31 +454,46 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou goto error; } + /* this lock makes sure we don't submit URBs to gone devices */ + mutex_lock(&dev->io_mutex); + if (!dev->interface) { /* disconnect() was called */ + mutex_unlock(&dev->io_mutex); + retval = -ENODEV; + goto error; + } + /* initialize the urb properly */ usb_fill_bulk_urb(urb, dev->udev, 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; + err("%s - failed submitting write urb, error %d", __func__, + retval); + goto error_unanchor; } - /* release our reference to this urb, the USB core will eventually free it entirely */ + /* + * release our reference to this urb, the USB core will eventually free + * it entirely + */ usb_free_urb(urb); - mutex_unlock(&dev->io_mutex); + return writesize; +error_unanchor: + usb_unanchor_urb(urb); error: if (urb) { usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma); usb_free_urb(urb); } - mutex_unlock(&dev->io_mutex); up(&dev->limit_sem); exit: @@ -260,6 +506,7 @@ static const struct file_operations skel_fops = { .write = skel_write, .open = skel_open, .release = skel_release, + .flush = skel_flush, }; /* @@ -272,7 +519,8 @@ static struct usb_class_driver skel_class = { .minor_base = USB_SKEL_MINOR_BASE, }; -static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id) +static int skel_probe(struct usb_interface *interface, + const struct usb_device_id *id) { struct usb_skel *dev; struct usb_host_interface *iface_desc; @@ -290,6 +538,9 @@ 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); + init_completion(&dev->bulk_in_completion); dev->udev = usb_get_dev(interface_to_usbdev(interface)); dev->interface = interface; @@ -311,6 +562,11 @@ static int skel_probe(struct usb_interface *interface, const struct usb_device_i err("Could not allocate bulk_in_buffer"); goto error; } + dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL); + if (!dev->bulk_in_urb) { + err("Could not allocate bulk_in_urb"); + goto error; + } } if (!dev->bulk_out_endpointAddr && @@ -337,11 +593,14 @@ static int skel_probe(struct usb_interface *interface, const struct usb_device_i } /* let the user know what node this device is now attached to */ - info("USB Skeleton device now attached to USBSkel-%d", interface->minor); + dev_info(&interface->dev, + "USB Skeleton device now attached to USBSkel-%d", + interface->minor); return 0; error: if (dev) + /* this frees allocated memory */ kref_put(&dev->kref, skel_delete); return retval; } @@ -351,9 +610,6 @@ static void skel_disconnect(struct usb_interface *interface) struct usb_skel *dev; int minor = interface->minor; - /* prevent skel_open() from racing skel_disconnect() */ - lock_kernel(); - dev = usb_get_intfdata(interface); usb_set_intfdata(interface, NULL); @@ -365,19 +621,70 @@ static void skel_disconnect(struct usb_interface *interface) dev->interface = NULL; mutex_unlock(&dev->io_mutex); - unlock_kernel(); + usb_kill_anchored_urbs(&dev->submitted); /* decrement our usage count */ kref_put(&dev->kref, skel_delete); - info("USB Skeleton #%d now disconnected", minor); + dev_info(&interface->dev, "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); + usb_kill_urb(dev->bulk_in_urb); +} + +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, }; static int __init usb_skel_init(void)