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authorHans de Goede <hdegoede@redhat.com>2012-09-08 20:02:05 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-09-10 11:10:37 -0700
commit0837e7e5270bd5547ba5763f11611dc43f677b3d (patch)
tree7815686351ce050a393cf5aecd52da5b92ea7119 /drivers/usb/core
parentba2f9dff6c914b91005f687a9d75c8eac110d323 (diff)
usbfs: Add a new disconnect-and-claim ioctl (v2)
Apps which deal with devices which also have a kernel driver, need to do the following: 1) Check which driver is attached, so as to not detach the wrong driver (ie detaching usbfs while another instance of the app is using the device) 2) Detach the kernel driver 3) Claim the interface Where moving from one step to the next for both 1-2 and 2-3 consists of a (small) race window. So currently such apps are racy and people just live with it. This patch adds a new ioctl which makes it possible for apps to do this in a race free manner. For flexibility apps can choose to: 1) Specify the driver to disconnect 2) Specify to disconnect any driver except for the one named by the app 3) Disconnect any driver Note that if there is no driver attached, the ioctl will just act like the regular claim-interface ioctl, this is by design, as returning an error for this condition would open a new bag of race-conditions. Changes in v2: -Fix indentation of if blocks where the condition spans multiple lines Signed-off-by: Hans de Goede <hdegoede@redhat.com> Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/core')
-rw-r--r--drivers/usb/core/devio.c35
1 files changed, 35 insertions, 0 deletions
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index ebb8a9de8b5..e0356cb859b 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1928,6 +1928,38 @@ static int proc_get_capabilities(struct dev_state *ps, void __user *arg)
return 0;
}
+static int proc_disconnect_claim(struct dev_state *ps, void __user *arg)
+{
+ struct usbdevfs_disconnect_claim dc;
+ struct usb_interface *intf;
+
+ if (copy_from_user(&dc, arg, sizeof(dc)))
+ return -EFAULT;
+
+ intf = usb_ifnum_to_if(ps->dev, dc.interface);
+ if (!intf)
+ return -EINVAL;
+
+ if (intf->dev.driver) {
+ struct usb_driver *driver = to_usb_driver(intf->dev.driver);
+
+ if ((dc.flags & USBDEVFS_DISCONNECT_CLAIM_IF_DRIVER) &&
+ strncmp(dc.driver, intf->dev.driver->name,
+ sizeof(dc.driver)) != 0)
+ return -EBUSY;
+
+ if ((dc.flags & USBDEVFS_DISCONNECT_CLAIM_EXCEPT_DRIVER) &&
+ strncmp(dc.driver, intf->dev.driver->name,
+ sizeof(dc.driver)) == 0)
+ return -EBUSY;
+
+ dev_dbg(&intf->dev, "disconnect by usbfs\n");
+ usb_driver_release_interface(driver, intf);
+ }
+
+ return claimintf(ps, dc.interface);
+}
+
/*
* NOTE: All requests here that have interface numbers as parameters
* are assuming that somehow the configuration has been prevented from
@@ -2101,6 +2133,9 @@ static long usbdev_do_ioctl(struct file *file, unsigned int cmd,
case USBDEVFS_GET_CAPABILITIES:
ret = proc_get_capabilities(ps, p);
break;
+ case USBDEVFS_DISCONNECT_CLAIM:
+ ret = proc_disconnect_claim(ps, p);
+ break;
}
usb_unlock_device(dev);
if (ret >= 0)