mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-07 18:36:40 +07:00
5b06470816
as the skeleton driver was made ready for autosuspend a race condition was introduced. The reference to get device must be gotten before the autosuspend counter is upped, as this operation may sleep, dropping BKL. Dropping BKL means that the pointer to the device may become invalid. Here's the fix. Signed-off-by: Oliver Neukum <oneukum@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
407 lines
10 KiB
C
407 lines
10 KiB
C
/*
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* USB Skeleton driver - 2.2
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*
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* Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2.
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*
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* This driver is based on the 2.6.3 version of drivers/usb/usb-skeleton.c
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* but has been rewritten to be easier to read and use.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/kref.h>
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#include <asm/uaccess.h>
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#include <linux/usb.h>
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#include <linux/mutex.h>
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/* Define these values to match your devices */
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#define USB_SKEL_VENDOR_ID 0xfff0
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#define USB_SKEL_PRODUCT_ID 0xfff0
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/* table of devices that work with this driver */
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static struct usb_device_id skel_table [] = {
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{ USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
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{ } /* Terminating entry */
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};
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MODULE_DEVICE_TABLE(usb, skel_table);
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/* Get a minor range for your devices from the usb maintainer */
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#define USB_SKEL_MINOR_BASE 192
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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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#define WRITES_IN_FLIGHT 8
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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 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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__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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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_delete(struct kref *kref)
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{
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struct usb_skel *dev = to_skel_dev(kref);
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usb_put_dev(dev->udev);
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kfree(dev->bulk_in_buffer);
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kfree(dev);
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}
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static int skel_open(struct inode *inode, struct file *file)
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{
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struct usb_skel *dev;
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struct usb_interface *interface;
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int subminor;
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int retval = 0;
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subminor = iminor(inode);
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interface = usb_find_interface(&skel_driver, subminor);
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if (!interface) {
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err ("%s - error, can't find device for minor %d",
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__FUNCTION__, subminor);
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retval = -ENODEV;
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goto exit;
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}
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dev = usb_get_intfdata(interface);
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if (!dev) {
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retval = -ENODEV;
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goto exit;
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}
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/* increment our usage count for the device */
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kref_get(&dev->kref);
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/* prevent the device from being autosuspended */
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retval = usb_autopm_get_interface(interface);
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if (retval) {
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kref_put(&dev->kref, skel_delete);
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goto exit;
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}
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/* save our object in the file's private structure */
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file->private_data = dev;
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exit:
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return retval;
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}
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static int skel_release(struct inode *inode, struct file *file)
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{
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struct usb_skel *dev;
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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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/* allow the device to be autosuspended */
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mutex_lock(&dev->io_mutex);
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if (dev->interface)
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usb_autopm_put_interface(dev->interface);
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mutex_unlock(&dev->io_mutex);
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/* decrement the count on our device */
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kref_put(&dev->kref, skel_delete);
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return 0;
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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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int retval;
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int bytes_read;
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dev = (struct usb_skel *)file->private_data;
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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 exit;
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}
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/* do a blocking bulk read to get data from the device */
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retval = usb_bulk_msg(dev->udev,
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usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
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dev->bulk_in_buffer,
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min(dev->bulk_in_size, count),
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&bytes_read, 10000);
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/* if the read was successful, copy the data to userspace */
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if (!retval) {
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if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
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retval = -EFAULT;
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else
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retval = bytes_read;
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}
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exit:
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mutex_unlock(&dev->io_mutex);
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return retval;
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}
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static void skel_write_bulk_callback(struct urb *urb)
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{
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struct usb_skel *dev;
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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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}
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/* free up our allocated buffer */
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usb_buffer_free(urb->dev, urb->transfer_buffer_length,
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urb->transfer_buffer, urb->transfer_dma);
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up(&dev->limit_sem);
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}
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static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos)
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{
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struct usb_skel *dev;
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int retval = 0;
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struct urb *urb = NULL;
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char *buf = NULL;
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size_t writesize = min(count, (size_t)MAX_TRANSFER);
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dev = (struct usb_skel *)file->private_data;
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/* verify that we actually have some data to write */
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if (count == 0)
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goto exit;
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/* limit the number of URBs in flight to stop a user from using up all RAM */
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if (down_interruptible(&dev->limit_sem)) {
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retval = -ERESTARTSYS;
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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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retval = -ENOMEM;
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goto error;
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}
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buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);
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if (!buf) {
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retval = -ENOMEM;
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goto error;
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}
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if (copy_from_user(buf, user_buffer, writesize)) {
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retval = -EFAULT;
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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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buf, writesize, skel_write_bulk_callback, dev);
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urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
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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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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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}
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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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if (urb) {
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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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return retval;
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}
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static const struct file_operations skel_fops = {
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.owner = THIS_MODULE,
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.read = skel_read,
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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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};
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/*
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* usb class driver info in order to get a minor number from the usb core,
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* and to have the device registered with the driver core
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*/
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static struct usb_class_driver skel_class = {
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.name = "skel%d",
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.fops = &skel_fops,
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.minor_base = USB_SKEL_MINOR_BASE,
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};
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static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id)
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{
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struct usb_skel *dev;
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struct usb_host_interface *iface_desc;
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struct usb_endpoint_descriptor *endpoint;
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size_t buffer_size;
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int i;
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int retval = -ENOMEM;
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/* allocate memory for our device state and initialize it */
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dev = kzalloc(sizeof(*dev), GFP_KERNEL);
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if (!dev) {
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err("Out of memory");
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goto error;
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}
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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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dev->udev = usb_get_dev(interface_to_usbdev(interface));
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dev->interface = interface;
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/* set up the endpoint information */
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/* use only the first bulk-in and bulk-out endpoints */
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iface_desc = interface->cur_altsetting;
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for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
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endpoint = &iface_desc->endpoint[i].desc;
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if (!dev->bulk_in_endpointAddr &&
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usb_endpoint_is_bulk_in(endpoint)) {
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/* we found a bulk in endpoint */
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buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
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dev->bulk_in_size = buffer_size;
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dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
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dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
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if (!dev->bulk_in_buffer) {
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err("Could not allocate bulk_in_buffer");
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goto error;
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}
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}
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if (!dev->bulk_out_endpointAddr &&
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usb_endpoint_is_bulk_out(endpoint)) {
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/* we found a bulk out endpoint */
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dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
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}
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}
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if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
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err("Could not find both bulk-in and bulk-out endpoints");
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goto error;
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}
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/* save our data pointer in this interface device */
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usb_set_intfdata(interface, dev);
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/* we can register the device now, as it is ready */
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retval = usb_register_dev(interface, &skel_class);
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if (retval) {
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/* something prevented us from registering this driver */
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err("Not able to get a minor for this device.");
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usb_set_intfdata(interface, NULL);
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goto error;
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}
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/* let the user know what node this device is now attached to */
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info("USB Skeleton device now attached to USBSkel-%d", interface->minor);
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return 0;
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error:
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if (dev)
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kref_put(&dev->kref, skel_delete);
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return retval;
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}
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static void skel_disconnect(struct usb_interface *interface)
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{
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struct usb_skel *dev;
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int minor = interface->minor;
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/* prevent skel_open() from racing skel_disconnect() */
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lock_kernel();
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dev = usb_get_intfdata(interface);
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usb_set_intfdata(interface, NULL);
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/* give back our minor */
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usb_deregister_dev(interface, &skel_class);
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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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info("USB Skeleton #%d now disconnected", minor);
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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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.disconnect = skel_disconnect,
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.id_table = skel_table,
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};
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static int __init usb_skel_init(void)
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{
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int result;
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/* register this driver with the USB subsystem */
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result = usb_register(&skel_driver);
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if (result)
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err("usb_register failed. Error number %d", result);
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return result;
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}
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static void __exit usb_skel_exit(void)
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{
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/* deregister this driver with the USB subsystem */
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usb_deregister(&skel_driver);
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}
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module_init(usb_skel_init);
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module_exit(usb_skel_exit);
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MODULE_LICENSE("GPL");
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