From: Tejun Heo <tj@kernel.org>
To: Namhyung Kim <namhyung@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-kernel@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>,
dm-devel@redhat.com
Subject: Re: [PATCH] block: add missing block_bio_complete() tracepoint
Date: Tue, 31 Jan 2012 02:39:47 -0800 [thread overview]
Message-ID: <CAOS58YP1F6_yBxRArcP4oyzAJVArLJB-ckjdXU35U1SNwi75XQ@mail.gmail.com> (raw)
In-Reply-To: <4F278A78.8080300@gmail.com>
Hello,
On Mon, Jan 30, 2012 at 10:30 PM, Namhyung Kim <namhyung@gmail.com> wrote:
> Right, but the point is it could make a NULL pointer dereference during
> evaluation of the argument of the TP AFAICS. I'm not sure about the TP
> implementation though, I think I was wrong - T_E_C() cannot protect us from
> it because it happens just before jumping to the TP, right?
>
> So I think we need a conditional jump (with the "likely" annotation) for
> this even when the TP is disabled.
Hmmm... still not following. Where the said NULL dereference happen?
TEC conditional is equivalent to "if (COND) TP;". If you don't use
TEC, it'll be "if (COND) if (TP enabled) TP;". With TEC, it will be
"if (TP enabled) if (COND) TP;". There's no other difference.
Thanks.
--
tejun
next prev parent reply other threads:[~2012-01-31 10:39 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-29 9:41 [PATCH] block: add missing block_bio_complete() tracepoint Namhyung Kim
2012-01-29 19:24 ` Tejun Heo
2012-01-30 1:44 ` Namhyung Kim
2012-01-30 1:47 ` Tejun Heo
2012-01-30 2:22 ` Namhyung Kim
2012-01-30 2:30 ` Tejun Heo
2012-01-30 2:49 ` Namhyung Kim
2012-01-30 2:53 ` Tejun Heo
2012-01-30 5:51 ` Namhyung Kim
2012-01-30 5:54 ` Tejun Heo
2012-01-30 6:02 ` Namhyung Kim
2012-01-30 6:38 ` Namhyung Kim
2012-01-30 17:05 ` Tejun Heo
2012-01-31 6:30 ` Namhyung Kim
2012-01-31 10:39 ` Tejun Heo [this message]
2012-02-01 2:18 ` Namhyung Kim
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