linux-kernel - Re: [PATCH 03/10] perf sched timehist: Handle zero sample->tid properly

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 for Android: free password hash cracker in your pocket

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

Message-ID: <CAM9d7cjUmAc4Q1CTGAPvobvNWVzzP3MT=nLBPwz+AM5ZtmoSug@mail.gmail.com>
Date:   Tue, 6 Dec 2016 12:59:27 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     David Ahern <dsahern@...il.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Olsa <jolsa@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Andi Kleen <andi@...stfloor.org>,
        Minchan Kim <minchan@...nel.org>
Subject: Re: [PATCH 03/10] perf sched timehist: Handle zero sample->tid properly

Hi David,

On Tue, Dec 6, 2016 at 12:52 PM, David Ahern <dsahern@...il.com> wrote:
> On 12/5/16 7:40 PM, Namhyung Kim wrote:
>> Sometimes samples have tid of 0 but non-0 pid.  It ends up having a
>
> Any idea how that happens?

No, I didn't investigate it yet.  Looking at the original code, you
seemed to have same issue and workaround like checking prev_pid or
callchains, right?

Thanks,
Namhyung

>
>> new thread of 0 tid/pid (instead of referring idle task) since tid is
>> used to search matching task.  But I guess it's wrong to use 0 as a
>> tid when pid is set.  This patch uses tid only if it has a non-zero
>> value or same as pid (of 0).