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| author | Alan Stern <stern@rowland.harvard.edu> | 2011-04-28 18:45:24 +0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-04-30 04:24:29 +0400 |
| commit | 6498d9db6d2dad4cf5deb2dd09e0816904f41ca5 (patch) | |
| tree | 68ebcb03c7d9fc1caf9205d96943ce46d0a08c4c | |
| parent | 15b2f3204a5c878c32939094775fb7349f707263 (diff) | |
| download | linux-6498d9db6d2dad4cf5deb2dd09e0816904f41ca5.tar.xz | |
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 <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | Documentation/usb/callbacks.txt | 8 | ||||
| -rw-r--r-- | include/linux/usb.h | 6 |
2 files changed, 9 insertions, 5 deletions
diff --git a/Documentation/usb/callbacks.txt b/Documentation/usb/callbacks.txt index bfb36b34b79e..9e85846bdb98 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. diff --git a/include/linux/usb.h b/include/linux/usb.h index 65f78ca5d88e..73c7df489607 100644 --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -806,8 +806,10 @@ struct usbdrv_wrap { * @resume: Called when the device is being resumed by the system. * @reset_resume: Called when the suspended device has been reset instead * of being resumed. - * @pre_reset: Called by usb_reset_device() when the device - * is about to be reset. + * @pre_reset: Called by usb_reset_device() when the device is about to be + * reset. This routine must not return until the driver has no active + * URBs for the device, and no more URBs may be submitted until the + * post_reset method is called. * @post_reset: Called by usb_reset_device() after the device * has been reset * @id_table: USB drivers use ID table to support hotplugging. |