On Sat, Jul 4, 2009 at 1:20 AM, Alan Stern<stern@xxxxxxxxxxxxxxxxxxx> wrote:
> 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
Good. Now urb creation is working with these changes.
Thanks for help.
Regards,
RD
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