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Commit 67f5dde3 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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USB: Fix a bug in usb_start_wait_urb 



This patch (as941) fixes a bug recently added to the USB synchronous
API.  The status of a completed URB must be preserved separately
across a completion callback.  Also, the actual_length value isn't
available until after the URB has fully completed.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent a12b8db0

drivers/usb/core/message.c

+16 −10
Original line number Diff line number Diff line
@@ -18,9 +18,17 @@ 
#include "hcd.h"	/* for usbcore internals */

#include "usb.h"



struct api_context {

	struct completion	done;

	int			status;

};



static void usb_api_blocking_completion(struct urb *urb)

{

	complete((struct completion *)urb->context);

	struct api_context *ctx = urb->context;



	ctx->status = urb->status;

	complete(&ctx->done);

}
@@ -32,20 +40,21 @@ static void usb_api_blocking_completion(struct urb *urb) 
 */

static int usb_start_wait_urb(struct urb *urb, int timeout, int *actual_length)

{ 

	struct completion done;

	struct api_context ctx;

	unsigned long expire;

	int retval;

	int status = urb->status;



	init_completion(&done); 	

	urb->context = &done;

	init_completion(&ctx.done);

	urb->context = &ctx;

	urb->actual_length = 0;

	retval = usb_submit_urb(urb, GFP_NOIO);

	if (unlikely(retval))

		goto out;



	expire = timeout ? msecs_to_jiffies(timeout) : MAX_SCHEDULE_TIMEOUT;

	if (!wait_for_completion_timeout(&done, expire)) {

	if (!wait_for_completion_timeout(&ctx.done, expire)) {

		usb_kill_urb(urb);

		retval = (ctx.status == -ENOENT ? -ETIMEDOUT : ctx.status);



		dev_dbg(&urb->dev->dev,

			"%s timed out on ep%d%s len=%d/%d\n",
@@ -54,11 +63,8 @@ static int usb_start_wait_urb(struct urb *urb, int timeout, int *actual_length) 
			usb_pipein(urb->pipe) ? "in" : "out",

			urb->actual_length,

			urb->transfer_buffer_length);



		usb_kill_urb(urb);

		retval = status == -ENOENT ? -ETIMEDOUT : status;

	} else

		retval = status;

		retval = ctx.status;

out:

	if (actual_length)

		*actual_length = urb->actual_length;