lkml.org 
[lkml]   [2012]   [Jan]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] block: add missing block_bio_complete() tracepoint
On Mon, Jan 30, 2012 at 03:38:57PM +0900, Namhyung Kim wrote:
> 2012-01-29 6:41 PM, Namhyung Kim wrote:
> >The block_bio_complete() TP has been missed so long, so that bio-based
> >drivers haven't been able to trace its IO behavior. Add it.
> >
> >In some rare cases, such as loop_switch, @bio->bi_bdev can be NULL.
> >Thus convert it to TRACE_EVENT_CONDITION() as Steven suggested.
> >
>
> Now I see that it seems TRACE_EVENT_CONDITION() can protect event
> tracing from such condition, but what about other users of the TP
> like blktrace? I think it'll still get NULL pointer dereference on
> bdev_get_queue() after the change, right? If so, convert to T_E_C()
> looks meaningless IMHO. Do I miss something?

Not really following, but the whole point of using
TRACE_EVENT_CONDITION() is avoiding the conditional jump when the TP
is disabled. Whether the TP users need to test again / more isn't too
important.

Thanks.

--
tejun


\
 
 \ /
  Last update: 2012-01-30 18:09    [W:0.056 / U:3.872 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site