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Commit 3f2cee73 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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USB: usbfs: allow URBs to be reaped after disconnection 



The usbfs API has a peculiar hole: Users are not allowed to reap their
URBs after the device has been disconnected.  There doesn't seem to be
any good reason for this; it is an ad-hoc inconsistency.

The patch allows users to issue the USBDEVFS_REAPURB and
USBDEVFS_REAPURBNDELAY ioctls (together with their 32-bit counterparts
on 64-bit systems) even after the device is gone.  If no URBs are
pending for a disconnected device then the ioctls will return -ENODEV
rather than -EAGAIN, because obviously no new URBs will ever be able
to complete.

The patch also adds a new capability flag for
USBDEVFS_GET_CAPABILITIES to indicate that the reap-after-disconnect
feature is supported.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Tested-by: default avatarChris Dickens <christopher.a.dickens@gmail.com>
Acked-by: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <greg@kroah.com>
parent 17136d49

drivers/usb/core/devio.c

+37 −26
Original line number Diff line number Diff line
@@ -1689,7 +1689,7 @@ static struct async *reap_as(struct usb_dev_state *ps) 
	for (;;) {

		__set_current_state(TASK_INTERRUPTIBLE);

		as = async_getcompleted(ps);

		if (as)

		if (as || !connected(ps))

			break;

		if (signal_pending(current))

			break;
@@ -1712,7 +1712,7 @@ static int proc_reapurb(struct usb_dev_state *ps, void __user *arg) 
	}

	if (signal_pending(current))

		return -EINTR;

	return -EIO;

	return -ENODEV;

}



static int proc_reapurbnonblock(struct usb_dev_state *ps, void __user *arg)
@@ -1721,10 +1721,11 @@ static int proc_reapurbnonblock(struct usb_dev_state *ps, void __user *arg) 
	struct async *as;



	as = async_getcompleted(ps);

	retval = -EAGAIN;

	if (as) {

		retval = processcompl(as, (void __user * __user *)arg);

		free_async(as);

	} else {

		retval = (connected(ps) ? -EAGAIN : -ENODEV);

	}

	return retval;

}
@@ -1854,7 +1855,7 @@ static int proc_reapurb_compat(struct usb_dev_state *ps, void __user *arg) 
	}

	if (signal_pending(current))

		return -EINTR;

	return -EIO;

	return -ENODEV;

}



static int proc_reapurbnonblock_compat(struct usb_dev_state *ps, void __user *arg)
@@ -1862,11 +1863,12 @@ static int proc_reapurbnonblock_compat(struct usb_dev_state *ps, void __user *ar 
	int retval;

	struct async *as;



	retval = -EAGAIN;

	as = async_getcompleted(ps);

	if (as) {

		retval = processcompl_compat(as, (void __user * __user *)arg);

		free_async(as);

	} else {

		retval = (connected(ps) ? -EAGAIN : -ENODEV);

	}

	return retval;

}
@@ -2038,7 +2040,8 @@ static int proc_get_capabilities(struct usb_dev_state *ps, void __user *arg) 
{

	__u32 caps;



	caps = USBDEVFS_CAP_ZERO_PACKET | USBDEVFS_CAP_NO_PACKET_SIZE_LIM;

	caps = USBDEVFS_CAP_ZERO_PACKET | USBDEVFS_CAP_NO_PACKET_SIZE_LIM |

			USBDEVFS_CAP_REAP_AFTER_DISCONNECT;

	if (!ps->dev->bus->no_stop_on_short)

		caps |= USBDEVFS_CAP_BULK_CONTINUATION;

	if (ps->dev->bus->sg_tablesize)
@@ -2138,6 +2141,32 @@ static long usbdev_do_ioctl(struct file *file, unsigned int cmd, 
		return -EPERM;



	usb_lock_device(dev);



	/* Reap operations are allowed even after disconnection */

	switch (cmd) {

	case USBDEVFS_REAPURB:

		snoop(&dev->dev, "%s: REAPURB\n", __func__);

		ret = proc_reapurb(ps, p);

		goto done;



	case USBDEVFS_REAPURBNDELAY:

		snoop(&dev->dev, "%s: REAPURBNDELAY\n", __func__);

		ret = proc_reapurbnonblock(ps, p);

		goto done;



#ifdef CONFIG_COMPAT

	case USBDEVFS_REAPURB32:

		snoop(&dev->dev, "%s: REAPURB32\n", __func__);

		ret = proc_reapurb_compat(ps, p);

		goto done;



	case USBDEVFS_REAPURBNDELAY32:

		snoop(&dev->dev, "%s: REAPURBNDELAY32\n", __func__);

		ret = proc_reapurbnonblock_compat(ps, p);

		goto done;

#endif

	}



	if (!connected(ps)) {

		usb_unlock_device(dev);

		return -ENODEV;
@@ -2231,16 +2260,6 @@ static long usbdev_do_ioctl(struct file *file, unsigned int cmd, 
			inode->i_mtime = CURRENT_TIME;

		break;



	case USBDEVFS_REAPURB32:

		snoop(&dev->dev, "%s: REAPURB32\n", __func__);

		ret = proc_reapurb_compat(ps, p);

		break;



	case USBDEVFS_REAPURBNDELAY32:

		snoop(&dev->dev, "%s: REAPURBNDELAY32\n", __func__);

		ret = proc_reapurbnonblock_compat(ps, p);

		break;



	case USBDEVFS_IOCTL32:

		snoop(&dev->dev, "%s: IOCTL32\n", __func__);

		ret = proc_ioctl_compat(ps, ptr_to_compat(p));
@@ -2252,16 +2271,6 @@ static long usbdev_do_ioctl(struct file *file, unsigned int cmd, 
		ret = proc_unlinkurb(ps, p);

		break;



	case USBDEVFS_REAPURB:

		snoop(&dev->dev, "%s: REAPURB\n", __func__);

		ret = proc_reapurb(ps, p);

		break;



	case USBDEVFS_REAPURBNDELAY:

		snoop(&dev->dev, "%s: REAPURBNDELAY\n", __func__);

		ret = proc_reapurbnonblock(ps, p);

		break;



	case USBDEVFS_DISCSIGNAL:

		snoop(&dev->dev, "%s: DISCSIGNAL\n", __func__);

		ret = proc_disconnectsignal(ps, p);
@@ -2304,6 +2313,8 @@ static long usbdev_do_ioctl(struct file *file, unsigned int cmd, 
		ret = proc_free_streams(ps, p);

		break;

	}



 done:

	usb_unlock_device(dev);

	if (ret >= 0)

		inode->i_atime = CURRENT_TIME;

include/uapi/linux/usbdevice_fs.h

+2 −1
Original line number Diff line number Diff line
@@ -128,11 +128,12 @@ struct usbdevfs_hub_portinfo { 
	char port [127];	/* e.g. port 3 connects to device 27 */

};



/* Device capability flags */

/* System and bus capability flags */

#define USBDEVFS_CAP_ZERO_PACKET		0x01

#define USBDEVFS_CAP_BULK_CONTINUATION		0x02

#define USBDEVFS_CAP_NO_PACKET_SIZE_LIM		0x04

#define USBDEVFS_CAP_BULK_SCATTER_GATHER	0x08

#define USBDEVFS_CAP_REAP_AFTER_DISCONNECT	0x10



/* USBDEVFS_DISCONNECT_CLAIM flags & struct */