From 6498d9db6d2dad4cf5deb2dd09e0816904f41ca5 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Thu, 28 Apr 2011 10:45:24 -0400 Subject: USB: documentation update for the pre_reset method This patch (as1459) updates the documentation for the pre_reset method in struct usb_driver. When a driver is notified of an impending reset, it must cancel all outstanding I/O and not start any new I/O until it has been notified that the reset is complete. As far as I know, most existing drivers that implement pre_reset do this now. The major exceptions appear to be the SpeedTouch and CDC-WDM drivers. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- Documentation/usb/callbacks.txt | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'Documentation/usb') diff --git a/Documentation/usb/callbacks.txt b/Documentation/usb/callbacks.txt index bfb36b34b79..9e85846bdb9 100644 --- a/Documentation/usb/callbacks.txt +++ b/Documentation/usb/callbacks.txt @@ -95,9 +95,11 @@ pre_reset int (*pre_reset)(struct usb_interface *intf); -Another driver or user space is triggering a reset on the device which -contains the interface passed as an argument. Cease IO and save any -device state you need to restore. +A driver or user space is triggering a reset on the device which +contains the interface passed as an argument. Cease IO, wait for all +outstanding URBs to complete, and save any device state you need to +restore. No more URBs may be submitted until the post_reset method +is called. If you need to allocate memory here, use GFP_NOIO or GFP_ATOMIC, if you are in atomic context. -- cgit v1.2.3-70-g09d2