[dm-devel] Re: [RFC PATCH 1/3] block: add rq->complete_io hook for request stacking

[Grant Grundler]

On Mon, Mar 3, 2008 at 8:24 AM, Hannes Reinecke <hare at suse.de> wrote:

>  I would rather have rq->complete_io() to be pointing to blk_end_io in the
>  default case, this way rq->complete_io() would always be valid and we
>  would be saving us the if() clause.

This is a good idea. But...

...
>  So when using my proposal this would just become:
>
>  {
>     BUG_ON(!rq->complete_io);
>
>     return rq->complete_io(rq, error, nr_bytes, 0, NULL);
>  }

This "BUG_ON" is also an "if()" clause except
it will panic. The box will panic if the function
pointer is a null pointer and it won't be hard to
sort out why. I suggest omitting the BUG_ON.

thanks,
grant