linux-kernel - Re: [PATCH -next] tracepoint: ipi: don't trace IPI on offline CPUs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 9 Mar 2016 16:40:16 +0000
From:	Sudeep Holla <sudeep.holla@....com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Sudeep Holla <sudeep.holla@....com>, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH -next] tracepoint: ipi: don't trace IPI on offline CPUs



On 09/03/16 16:05, Steven Rostedt wrote:
> On Wed,  9 Mar 2016 12:22:22 +0000
> Sudeep Holla <sudeep.holla@....com> wrote:
>
>
>> Hi Steven,
>>
>> I observed that in "include/linux/tracepoint.h", we have
>> #define __DO_TRACE(tp, proto, args, cond, prercu, postrcu)
>> ...
>>                   if (!cpu_online(raw_smp_processor_id()))
>>                           return;
>>
>>                   if (!(cond))
>>                           return;
>> ...
>>
>> where !cond check seems reduntant if it's cpu_online check.
>> So, does this patch handle the warning correctly or is there any better
>> way ? I did see few traces with same condition, just thought of checking
>> with you.
>>
>
> Bah, I forgot that we have lockdep checks for when the event isn't
> enabled.

Yes I was about to ask you the same. I did further digging to check if I
was missing something after seeing your series[1] especially patch 2/12
(tracing: Remove duplicate checks for online CPUs)

> Can you try this patch:

It works. Thanks for the quick fix.

Tested-by: Sudeep Holla <sudeep.holla@....com>

--
Regards,
Sudeep

[1] http://www.spinics.net/lists/kernel/msg2208604.html