[dm-devel] [PATCH] block: add missing block_bio_complete() tracepoint
Tejun Heo
tj at kernel.org
Tue Jan 31 10:39:47 UTC 2012
Hello,
On Mon, Jan 30, 2012 at 10:30 PM, Namhyung Kim <namhyung at 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
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