On 4/24/07, Oliver Neukum <[EMAIL PROTECTED]> wrote:
> Am Dienstag, 24. April 2007 12:06 schrieb Wael Adel:
> > On 4/24/07, Oliver Neukum <[EMAIL PROTECTED]> wrote:
> > > Am Dienstag, 24. April 2007 11:46 schrieb Wael Adel:
> > > > retval = usb_submit_urb(urb, GFP_KERNEL);
> > > > if (retval) {
> > > > err("%s - failed submitting write urb, error %d",
> > > __FUNCTION__, retval);
> > > > goto error;
> > > > }
> > > >
> > > > if (buf != NULL)
> > > > {
> > > > if (copy_to_user(user_buffer, buf , readsize))
> > > > {
> > > > retval = -EFAULT;
> > > > goto error;
> > > > }
> > > > }
> > >
> > > You are copying the the buffer to user space without waiting for the
> > > URB to be executed. That cannot work.
> >
> > so how can i wait for the urb to be executed then copying the data to
> > the user space?
> > is there a flag that i should loop on it or what?
>
> - init an instance of "struct completion"
> - submit the URB, passing a pointer to the struct completion
> - use wait_for_completion()
>
> - in the completion handler call complete()
so these are the required modifications required to wait until the urb
is finished then i can transfer the read data to the user-space
***********************************************************************************************************************
static void skel_read_bulk_callback(struct urb *urb, struct pt_regs *regs)
{
struct usb_skel *dev;
complete((struct completion *)urb->context);
dev = (struct usb_skel *)urb->context;
/* sync/async unlink faults aren't errors */
if (urb->status &&
!(urb->status == -ENOENT ||
urb->status == -ECONNRESET ||
urb->status == -ESHUTDOWN)) {
dbg("%s - nonzero write bulk status received: %d",
__FUNCTION__, urb->status);
}
/* free up our allocated buffer */
usb_buffer_free(urb->dev, urb->transfer_buffer_length,
urb->transfer_buffer, urb->transfer_dma);
up(&dev->limit_sem);
}
static ssize_t skel_read(struct file *file, const char *user_buffer,
size_t count, loff_t *ppos)
{
struct completion done;
struct usb_skel *dev;
int retval = 0,readbytes;
struct urb *urb = NULL;
char *buf = NULL;
size_t readsize = min(count, (size_t)MAX_TRANSFER);
dev = (struct usb_skel *)file->private_data;
/* verify that we actually have some data to write */
if (count == 0)
goto exit;
/* limit the number of URBs in flight to stop a user from using up all
RAM */
if (down_interruptible(&dev->limit_sem)) {
retval = -ERESTARTSYS;
goto exit;
}
/* create a urb, and a buffer for it, and copy the data to the urb */
urb = usb_alloc_urb(0, GFP_KERNEL);
if (!urb) {
retval = -ENOMEM;
goto error;
}
buf = usb_buffer_alloc(dev->udev, readsize, GFP_KERNEL,
&urb->transfer_dma);
if (!buf) {
retval = -ENOMEM;
goto error;
}
/* initialize the urb properly */
usb_fill_bulk_urb(urb, dev->udev,
usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
buf, readsize, skel_read_bulk_callback, dev);
urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
/* send the data out the bulk port */
retval = usb_submit_urb(urb, GFP_KERNEL);
if (retval) {
err("%s - failed submitting write urb, error %d", __FUNCTION__,
retval);
goto error;
}
wait_for_completion(&done);
if ( copy_to_user(user_buffer, dev->bulk_in_buffer, readbytes) )
retval = -EFAULT;
else
retval = readbytes;
return retval;
/* release our reference to this urb, the USB core will eventually
free it entirely */
usb_free_urb(urb);
exit:
return readsize;
error:
usb_buffer_free(dev->udev, readsize, buf, urb->transfer_dma);
usb_free_urb(urb);
up(&dev->limit_sem);
return retval;
}
*********************************************************************************************************************
is it right? or there is something else i should adjust.
thanks in advance.
>
> HTH
> Oliver
> --
> SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
> This signature is a legal requirement
>
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