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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: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2007-07-24 18:23:23 -04:00 committed by Greg Kroah-Hartman
parent a12b8db020
commit 67f5dde3d4
1 changed files with 16 additions and 10 deletions
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26
drivers/usb/core/message.c
View File

@ -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;