On Sat, 4 Jul 2009, Ramya Desai wrote:
> Dear Experts,
>
> I am trying to create a new URB in the completion call back.
> Here I am giving the code that I am using.
>
> void my_usb_stor_blocking_completion(struct urb *urb)
> {
>
> struct urb *rr_urb ;
>
> //
> //
> //
>
> rr_urb = (struct urb*)kmalloc(sizeof(struct urb), GFP_KERNEL);
Don't use kmalloc to allocate URBs; use usb_alloc_urb.
You must not use GFP_KERNEL in a completion routine. Use GFP_ATOMIC
instead.
> if( NULL == rr_urb)
> return -ENOMEM;
You can't return -ENOMEM because this function returns void.
> memcpy(rr_urb, urb, sizeof(struct urb));
Why do the memcpy? usb_fill_bulk_urb will just overwrite the data.
> usb_fill_bulk_urb(rr_urb,
> current_urb_context->pusb_dev, current_urb_context->stat_bulkin_pipe,
> prd_ready, 4,
> my_usb_stor_blocking_completion,(void*)current_urb_context);
>
> //
> //
> //
>
> }
>
> With this code, the system is going to hanging.
> Is there any thing I need to do while creating a URB ?
Fix those mistakes. No other special action is needed.
In fact, you might not have to create a new URB at all. You might be
able to re-use the URB that was passed to
my_usb_stor_blocking_completion().
Alan Stern
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