kernel-fxtec-pro1x/drivers/media/usb/uvc/uvc_status.c
Laurent Pinchart 17706f5653 [media] uvcvideo: Fix open/close race condition
Maintaining the users count using an atomic variable makes sure that
access to the counter won't be racy, but doesn't serialize access to the
operations protected by the counter. This creates a race condition that
could result in the status URB being submitted multiple times.
Use a mutex to protect the users count and serialize access to the
status start and stop operations.

Reported-by: Shawn Nematbakhsh <shawnn@chromium.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2013-06-08 19:51:16 -03:00

220 lines
5.2 KiB
C

/*
* uvc_status.c -- USB Video Class driver - Status endpoint
*
* Copyright (C) 2005-2009
* Laurent Pinchart (laurent.pinchart@ideasonboard.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
*/
#include <linux/kernel.h>
#include <linux/input.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/usb/input.h>
#include "uvcvideo.h"
/* --------------------------------------------------------------------------
* Input device
*/
#ifdef CONFIG_USB_VIDEO_CLASS_INPUT_EVDEV
static int uvc_input_init(struct uvc_device *dev)
{
struct input_dev *input;
int ret;
input = input_allocate_device();
if (input == NULL)
return -ENOMEM;
usb_make_path(dev->udev, dev->input_phys, sizeof(dev->input_phys));
strlcat(dev->input_phys, "/button", sizeof(dev->input_phys));
input->name = dev->name;
input->phys = dev->input_phys;
usb_to_input_id(dev->udev, &input->id);
input->dev.parent = &dev->intf->dev;
__set_bit(EV_KEY, input->evbit);
__set_bit(KEY_CAMERA, input->keybit);
if ((ret = input_register_device(input)) < 0)
goto error;
dev->input = input;
return 0;
error:
input_free_device(input);
return ret;
}
static void uvc_input_cleanup(struct uvc_device *dev)
{
if (dev->input)
input_unregister_device(dev->input);
}
static void uvc_input_report_key(struct uvc_device *dev, unsigned int code,
int value)
{
if (dev->input) {
input_report_key(dev->input, code, value);
input_sync(dev->input);
}
}
#else
#define uvc_input_init(dev)
#define uvc_input_cleanup(dev)
#define uvc_input_report_key(dev, code, value)
#endif /* CONFIG_USB_VIDEO_CLASS_INPUT_EVDEV */
/* --------------------------------------------------------------------------
* Status interrupt endpoint
*/
static void uvc_event_streaming(struct uvc_device *dev, __u8 *data, int len)
{
if (len < 3) {
uvc_trace(UVC_TRACE_STATUS, "Invalid streaming status event "
"received.\n");
return;
}
if (data[2] == 0) {
if (len < 4)
return;
uvc_trace(UVC_TRACE_STATUS, "Button (intf %u) %s len %d\n",
data[1], data[3] ? "pressed" : "released", len);
uvc_input_report_key(dev, KEY_CAMERA, data[3]);
} else {
uvc_trace(UVC_TRACE_STATUS, "Stream %u error event %02x %02x "
"len %d.\n", data[1], data[2], data[3], len);
}
}
static void uvc_event_control(struct uvc_device *dev, __u8 *data, int len)
{
char *attrs[3] = { "value", "info", "failure" };
if (len < 6 || data[2] != 0 || data[4] > 2) {
uvc_trace(UVC_TRACE_STATUS, "Invalid control status event "
"received.\n");
return;
}
uvc_trace(UVC_TRACE_STATUS, "Control %u/%u %s change len %d.\n",
data[1], data[3], attrs[data[4]], len);
}
static void uvc_status_complete(struct urb *urb)
{
struct uvc_device *dev = urb->context;
int len, ret;
switch (urb->status) {
case 0:
break;
case -ENOENT: /* usb_kill_urb() called. */
case -ECONNRESET: /* usb_unlink_urb() called. */
case -ESHUTDOWN: /* The endpoint is being disabled. */
case -EPROTO: /* Device is disconnected (reported by some
* host controller). */
return;
default:
uvc_printk(KERN_WARNING, "Non-zero status (%d) in status "
"completion handler.\n", urb->status);
return;
}
len = urb->actual_length;
if (len > 0) {
switch (dev->status[0] & 0x0f) {
case UVC_STATUS_TYPE_CONTROL:
uvc_event_control(dev, dev->status, len);
break;
case UVC_STATUS_TYPE_STREAMING:
uvc_event_streaming(dev, dev->status, len);
break;
default:
uvc_trace(UVC_TRACE_STATUS, "Unknown status event "
"type %u.\n", dev->status[0]);
break;
}
}
/* Resubmit the URB. */
urb->interval = dev->int_ep->desc.bInterval;
if ((ret = usb_submit_urb(urb, GFP_ATOMIC)) < 0) {
uvc_printk(KERN_ERR, "Failed to resubmit status URB (%d).\n",
ret);
}
}
int uvc_status_init(struct uvc_device *dev)
{
struct usb_host_endpoint *ep = dev->int_ep;
unsigned int pipe;
int interval;
if (ep == NULL)
return 0;
uvc_input_init(dev);
dev->status = kzalloc(UVC_MAX_STATUS_SIZE, GFP_KERNEL);
if (dev->status == NULL)
return -ENOMEM;
dev->int_urb = usb_alloc_urb(0, GFP_KERNEL);
if (dev->int_urb == NULL) {
kfree(dev->status);
return -ENOMEM;
}
pipe = usb_rcvintpipe(dev->udev, ep->desc.bEndpointAddress);
/* For high-speed interrupt endpoints, the bInterval value is used as
* an exponent of two. Some developers forgot about it.
*/
interval = ep->desc.bInterval;
if (interval > 16 && dev->udev->speed == USB_SPEED_HIGH &&
(dev->quirks & UVC_QUIRK_STATUS_INTERVAL))
interval = fls(interval) - 1;
usb_fill_int_urb(dev->int_urb, dev->udev, pipe,
dev->status, UVC_MAX_STATUS_SIZE, uvc_status_complete,
dev, interval);
return 0;
}
void uvc_status_cleanup(struct uvc_device *dev)
{
usb_kill_urb(dev->int_urb);
usb_free_urb(dev->int_urb);
kfree(dev->status);
uvc_input_cleanup(dev);
}
int uvc_status_start(struct uvc_device *dev, gfp_t flags)
{
if (dev->int_urb == NULL)
return 0;
return usb_submit_urb(dev->int_urb, flags);
}
void uvc_status_stop(struct uvc_device *dev)
{
usb_kill_urb(dev->int_urb);
}