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From: Jeff Moyer <jmoyer@redhat.com>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Jens Axboe <axboe@kernel.dk>, Steven Rostedt <rostedt@goodmis.org>,
        Frederic Weisbecker <fweisbec@gmail.com>, Ingo Molnar <mingo@elte.hu>,
        Thomas Gleixner <tglx@linutronix.de>, Li Zefan <lizf@cn.fujitsu.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] blktrace: add missing probe argument to block_bio_complete
References: <20110107015453.GB5109@Krystal>
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Date: Fri, 07 Jan 2011 09:13:52 -0500
In-Reply-To: <20110107015453.GB5109@Krystal> (Mathieu Desnoyers's message of
	"Thu, 6 Jan 2011 20:54:53 -0500")
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Mathieu Desnoyers <mathieu.desnoyers@efficios.com> writes:

> blktrace.c block bio complete callback needs to gain a new argument to reflect
> the newly added "error" tracepoint argument. This is needed to match the new
> block_bio_complete TRACE_EVENT as of
> commit de983a7bfcb7c020901ca6e2314cf55a4207ab5a.
>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> CC: Jeff Moyer <jmoyer@redhat.com>
> CC: Steven Rostedt <rostedt@goodmis.org>
> CC: Frederic Weisbecker <fweisbec@gmail.com>
> CC: Ingo Molnar <mingo@elte.hu>
> CC: Thomas Gleixner <tglx@linutronix.de>
> CC: Jens Axboe <axboe@kernel.dk>
> CC: Li Zefan <lizf@cn.fujitsu.com>
> ---
>  kernel/trace/blktrace.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> Index: linux-2.6-lttng/kernel/trace/blktrace.c
> ===================================================================
> --- linux-2.6-lttng.orig/kernel/trace/blktrace.c
> +++ linux-2.6-lttng/kernel/trace/blktrace.c
> @@ -785,7 +785,8 @@ static void blk_add_trace_bio_bounce(voi
>  }
>  
>  static void blk_add_trace_bio_complete(void *ignore,
> -				       struct request_queue *q, struct bio *bio)
> +				       struct request_queue *q, struct bio *bio,
> +				       int error)
>  {
>  	blk_add_trace_bio(q, bio, BLK_TA_COMPLETE);
>  }

OK, I clearly didn't look closely enough last time.  There's no sense
passing this information down if it isn't used (as you said initially).
blk_add_trace_bio sets the error based on whether or not the
BIO_UPTODATE bit is set.  So, I think we should instead revert the patch
I sent you (Mathieu), and then completely get rid of the error field in
the TP macros.

Does that make sense to everyone else?

Cheers,
Jeff