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USB: usbfs: allow URBs to be reaped after disconnection

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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: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Chris Dickens <christopher.a.dickens@gmail.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
This commit is contained in:
Alan Stern
2015-01-29 11:29:13 -05:00
committed by Greg Kroah-Hartman
parent 17136d4984
commit 3f2cee73b6
2 changed files with 39 additions and 27 deletions
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3
include/uapi/linux/usbdevice_fs.h
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@@ -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 */