V4L/DVB (9647): em28xx: void having two concurrent control URB's
Now that we have a polling task for IR, there's a race condition, since
IR can be polling while other operations are being doing. Also, we are
now sharing the same urb_buf for both read and write control urb
operations. So, we need a mutex.
Thanks to Davin Heitmueller <devin.heitmueller@gmail.com> for warning me.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/em28xx/em28xx-core.c b/drivers/media/video/em28xx/em28xx-core.c
index 9551b8a..15e2b52 100644
--- a/drivers/media/video/em28xx/em28xx-core.c
+++ b/drivers/media/video/em28xx/em28xx-core.c
@@ -76,18 +76,22 @@
em28xx_regdbg("req=%02x, reg=%02x ", req, reg);
+ mutex_lock(&dev->ctrl_urb_lock);
ret = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0), req,
USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
0x0000, reg, dev->urb_buf, len, HZ);
if (ret < 0) {
if (reg_debug)
printk(" failed!\n");
+ mutex_unlock(&dev->ctrl_urb_lock);
return ret;
}
if (len)
memcpy(buf, dev->urb_buf, len);
+ mutex_unlock(&dev->ctrl_urb_lock);
+
if (reg_debug) {
printk("%02x values: ", ret);
for (byte = 0; byte < len; byte++)
@@ -112,16 +116,18 @@
em28xx_regdbg("req=%02x, reg=%02x:", req, reg);
+ mutex_lock(&dev->ctrl_urb_lock);
ret = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0), req,
USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
0x0000, reg, dev->urb_buf, 1, HZ);
+ val = dev->urb_buf[0];
+ mutex_unlock(&dev->ctrl_urb_lock);
+
if (ret < 0) {
printk(" failed!\n");
return ret;
}
- val = dev->urb_buf[0];
-
if (reg_debug)
printk("%02x\n", (unsigned char) val);
@@ -156,10 +162,12 @@
printk("\n");
}
+ mutex_lock(&dev->ctrl_urb_lock);
memcpy(dev->urb_buf, buf, len);
ret = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0), req,
USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
0x0000, reg, dev->urb_buf, len, HZ);
+ mutex_unlock(&dev->ctrl_urb_lock);
if (dev->wait_after_write)
msleep(dev->wait_after_write);
