linux-kernel - Re: [PATCH V2 1/1] tick: broadcast-hrtimer: Fix a race in bc_set

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Message-ID: <alpine.DEB.2.21.1909261144250.5528@nanos.tec.linutronix.de>
Date:   Thu, 26 Sep 2019 12:01:48 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Balasubramani Vivekanandan <balasubramani_vivekanandan@...tor.com>
cc:     fweisbec@...il.com, mingo@...nel.org, peterz@...radead.org,
        erosca@...adit-jv.com, linux-renesas-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 1/1] tick: broadcast-hrtimer: Fix a race in
 bc_set_next

On Wed, 25 Sep 2019, Balasubramani Vivekanandan wrote:
> 
> Since it is now allowed to start the hrtimer from the callback, there is

Is now allowed? 

> no need for the try to cancel logic. All that is now removed.

Sure I can see that it is removed from the patch, but why and why is it
correct?

> [1]: rcu stall warnings noticed before this patch
> 
> [   26.477514] INFO: rcu_preempt detected stalls on CPUs/tasks:

<SNIP>

I which way is this backtrace giving any useful information about the
problem?

> 
> Signed-off-by: Balasubramani Vivekanandan <balasubramani_vivekanandan@...tor.com>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

Interesting. You claim authorship on that patch and then you put my SOB
after yours just because you feel entitled to do so?

I surely appreciate the time you spent to analyze the problem and I
wouldn't have said anything if you just would have done the right thing:

 1) Write a changelog which explains why the change is actually correct

 2) Not wreckage the formatting which I intentionally did for readability
    sake

 3) Add 'Originally-by: Thomas Gleixner' or at least having the courtesy to
    mention that this is not your work.

Thanks,

	tglx