From: Alan Stern <stern@rowland.harvard.edu>
Date: Tue, 24 Sep 2013 19:43:39 +0000 (-0400)
Subject: USB: fix substandard locking for the sysfs files
X-Git-Tag: omap-for-v3.13/fixes-for-merge-window-take2~66^2~165
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=232275a089dfd2e77377a85f11d0a4e3ca60e612;p=pandora-kernel.git

USB: fix substandard locking for the sysfs files

This patch straightens out some locking issues in the USB sysfs
interface:

	Deauthorization will destroy existing configurations.
	Attributes that read from udev->actconfig need to lock the
	device to prevent races.  Likewise for the rawdescriptor
	values.

	Attributes that access an interface's current alternate
	setting should use ACCESS_ONCE() to obtain the cur_altsetting
	pointer, to protect against concurrent altsetting changes.

	The supports_autosuspend() attribute routine accesses values
	from an interface's driver, so it should lock the interface
	(rather than the usb_device) to protect against concurrent
	unbinds.  Once this is done, the routine can be simplified
	considerably.

Scalar values that are stored directly in the usb_device structure are
always available.  They do not require any locking.  The same is true
of the cached interface string descriptor, because it is not
deallocated until the usb_host_interface structure is destroyed.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

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