Re: [PATCH] clocksource/drivers/arm_arch_timer: Fix event stream param in Kconfig

From: Marc Zyngier <maz@kernel.org>
To: "Tyler Hicks (Microsoft)" <code@tyhicks.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vijay Balakrishna <vijayb@linux.microsoft.com>,
	Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] clocksource/drivers/arm_arch_timer: Fix event stream param in Kconfig
Date: Tue, 25 Oct 2022 16:07:28 +0100	[thread overview]
Message-ID: <86mt9kdjrj.wl-maz@kernel.org> (raw)
In-Reply-To: <20221025141854.22ppd7mw3vb6esgr@sequoia>

Hi Tyler,

On Tue, 25 Oct 2022 15:18:54 +0100,
"Tyler Hicks (Microsoft)" <code@tyhicks.com> wrote:
> 
> On 2022-10-25 11:24:55, Marc Zyngier wrote:
> > Hi Tyler,
> > 
> > On Mon, 24 Oct 2022 20:51:18 +0100,
> > Tyler Hicks <code@tyhicks.com> wrote:
> > > 
> > > From: "Tyler Hicks (Microsoft)" <code@tyhicks.com>
> > > 
> > > Fix the event stream timer command line parameter name that's documented
> > > in the Kconfig description for CONFIG_ARM_ARCH_TIMER_EVTSTREAM. It
> > > didn't match the command line parameter name that's actually honored in
> > > the source code.
> > > 
> > > Reported-by: Vijay Balakrishna <vijayb@linux.microsoft.com>
> > > Fixes: 46fd5c6b3059 ("clocksource/drivers/arm_arch_timer: Control the evtstrm via the cmdline")
> > > Cc: stable@vger.kernel.org
> > 
> > No, this really doesn't deserve a Cc: stable. This bit may be wrong,
> > but we have the correct information in the kernel-parameters.txt file,
> > which is authoritative AFAIC.
> 
> Thanks for the review!
> 
> I added the stable tag because it caused an actual waste of time in an
> investigation. Upon discovering this option, I didn't notice the subtle
> difference in cmdline parameter name from the Kconfig, to the
> kernel-parameters.txt file and the code. I ran long-running stress tests
> with the incorrect parameter name copied and pasted from the Kconfig.
> This error resulted in a bad data point in the investigation and it took
> a second set of eyes (Vijay's) to uncover my mistake days later when we
> were trying to reconcile the bad data point with other good data points.

I appreciate this has caused a certain waste of time, but the rules
for stable inclusion are pretty clear: it has to be a runtime bug.
Documentation bugs, as irritating as they are, do not fall into this
category (it really *is* a typo).

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

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