From: Petr Mladek <pmladek@suse.com>
To: Douglas Anderson <dianders@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
kgdb-bugreport@lists.sourceforge.net,
linux-kernel@vger.kernel.org, Nicholas Piggin <npiggin@gmail.com>,
Michael Ellerman <mpe@ellerman.id.au>,
linuxppc-dev@lists.ozlabs.org,
Christophe Leroy <christophe.leroy@csgroup.eu>,
sparclinux@vger.kernel.org,
"David S . Miller" <davem@davemloft.net>,
linux-perf-users@vger.kernel.org
Subject: Re: [PATCH 02/10] watchdog/hardlockup: HAVE_NMI_WATCHDOG must implement watchdog_hardlockup_probe()
Date: Tue, 30 May 2023 16:38:02 +0200 [thread overview]
Message-ID: <ZHYKSnLBU82fM1O2@alley> (raw)
In-Reply-To: <20230526184139.2.Ic6ebbf307ca0efe91f08ce2c1eb4a037ba6b0700@changeid>
On Fri 2023-05-26 18:41:32, Douglas Anderson wrote:
> Right now there is one arch (sparc64) that selects HAVE_NMI_WATCHDOG
> without selecting HAVE_HARDLOCKUP_DETECTOR_ARCH. Because of that one
> architecture, we have some special case code in the watchdog core to
> handle the fact that watchdog_hardlockup_probe() isn't implemented.
>
> Let's implement watchdog_hardlockup_probe() for sparc64 and get rid of
> the special case.
>
> As a side effect of doing this, code inspection tells us that we could
> fix a minor bug where the system won't properly realize that NMI
> watchdogs are disabled. Specifically, on powerpc if
> CONFIG_PPC_WATCHDOG is turned off the arch might still select
> CONFIG_HAVE_HARDLOCKUP_DETECTOR_ARCH which selects
> CONFIG_HAVE_NMI_WATCHDOG. Since CONFIG_PPC_WATCHDOG was off then
> nothing will override the "weak" watchdog_hardlockup_probe() and we'll
> fallback to looking at CONFIG_HAVE_NMI_WATCHDOG.
>
> Suggested-by: Petr Mladek <pmladek@suse.com>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
Looks good:
Reviewed-by: Petr Mladek <pmladek@suse.com>
> ---
> Though this does fix a minor bug, I didn't mark this as "Fixes"
> because it's super minor. One could also argue that this wasn't a bug
> at all but simply was never an implemented feature. The code that
> added some amount of dynamicness here was commit a994a3147e4c
> ("watchdog/hardlockup/perf: Implement init time detection of perf")
> which, as per the title, was only intending to make "perf"
> dynamic. The old NMI watchdog presumably has never been handled
> dynamically.
I agree that it is a minor bug and Fixes tag is not needed.
Another motivation is that all the dependencies are quite
complicated. IMHO, it is not worth spending time on
reviewing potential backports.
That said, I am afraid that the artificial intelligence will nominate
this patch for stable backports even without the Fixes tag.
You know, there are the words "fix" and "bug" in the commit message ;-)
Best Regards,
Petr
WARNING: multiple messages have this Message-ID (diff)
From: Petr Mladek <pmladek@suse.com>
To: Douglas Anderson <dianders@chromium.org>
Cc: kgdb-bugreport@lists.sourceforge.net,
linux-kernel@vger.kernel.org, Nicholas Piggin <npiggin@gmail.com>,
linux-perf-users@vger.kernel.org, sparclinux@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev@lists.ozlabs.org,
"David S . Miller" <davem@davemloft.net>
Subject: Re: [PATCH 02/10] watchdog/hardlockup: HAVE_NMI_WATCHDOG must implement watchdog_hardlockup_probe()
Date: Tue, 30 May 2023 16:38:02 +0200 [thread overview]
Message-ID: <ZHYKSnLBU82fM1O2@alley> (raw)
In-Reply-To: <20230526184139.2.Ic6ebbf307ca0efe91f08ce2c1eb4a037ba6b0700@changeid>
On Fri 2023-05-26 18:41:32, Douglas Anderson wrote:
> Right now there is one arch (sparc64) that selects HAVE_NMI_WATCHDOG
> without selecting HAVE_HARDLOCKUP_DETECTOR_ARCH. Because of that one
> architecture, we have some special case code in the watchdog core to
> handle the fact that watchdog_hardlockup_probe() isn't implemented.
>
> Let's implement watchdog_hardlockup_probe() for sparc64 and get rid of
> the special case.
>
> As a side effect of doing this, code inspection tells us that we could
> fix a minor bug where the system won't properly realize that NMI
> watchdogs are disabled. Specifically, on powerpc if
> CONFIG_PPC_WATCHDOG is turned off the arch might still select
> CONFIG_HAVE_HARDLOCKUP_DETECTOR_ARCH which selects
> CONFIG_HAVE_NMI_WATCHDOG. Since CONFIG_PPC_WATCHDOG was off then
> nothing will override the "weak" watchdog_hardlockup_probe() and we'll
> fallback to looking at CONFIG_HAVE_NMI_WATCHDOG.
>
> Suggested-by: Petr Mladek <pmladek@suse.com>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
Looks good:
Reviewed-by: Petr Mladek <pmladek@suse.com>
> ---
> Though this does fix a minor bug, I didn't mark this as "Fixes"
> because it's super minor. One could also argue that this wasn't a bug
> at all but simply was never an implemented feature. The code that
> added some amount of dynamicness here was commit a994a3147e4c
> ("watchdog/hardlockup/perf: Implement init time detection of perf")
> which, as per the title, was only intending to make "perf"
> dynamic. The old NMI watchdog presumably has never been handled
> dynamically.
I agree that it is a minor bug and Fixes tag is not needed.
Another motivation is that all the dependencies are quite
complicated. IMHO, it is not worth spending time on
reviewing potential backports.
That said, I am afraid that the artificial intelligence will nominate
this patch for stable backports even without the Fixes tag.
You know, there are the words "fix" and "bug" in the commit message ;-)
Best Regards,
Petr
next prev parent reply other threads:[~2023-05-30 14:38 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-27 1:41 [PATCH 00/10] watchdog: Cleanup / fixes after buddy series v5 reviews Douglas Anderson
2023-05-27 1:41 ` Douglas Anderson
2023-05-27 1:41 ` [PATCH 01/10] watchdog/hardlockup: Keep kernel.nmi_watchdog sysctl as 0444 if probe fails Douglas Anderson
2023-05-27 1:41 ` Douglas Anderson
2023-05-30 14:15 ` Petr Mladek
2023-05-30 14:15 ` Petr Mladek
2023-05-27 1:41 ` [PATCH 02/10] watchdog/hardlockup: HAVE_NMI_WATCHDOG must implement watchdog_hardlockup_probe() Douglas Anderson
2023-05-27 1:41 ` Douglas Anderson
2023-05-30 14:38 ` Petr Mladek [this message]
2023-05-30 14:38 ` Petr Mladek
2023-05-27 1:41 ` [PATCH 03/10] watchdog/hardlockup: Don't use raw_cpu_ptr() in watchdog_hardlockup_kick() Douglas Anderson
2023-05-27 1:41 ` Douglas Anderson
2023-05-30 14:39 ` Petr Mladek
2023-05-30 14:39 ` Petr Mladek
2023-05-27 1:41 ` [PATCH 04/10] watchdog/hardlockup: In watchdog_hardlockup_check() use cpumask_copy() Douglas Anderson
2023-05-27 1:41 ` Douglas Anderson
2023-05-30 14:40 ` Petr Mladek
2023-05-30 14:40 ` Petr Mladek
2023-05-27 1:41 ` [PATCH 05/10] watchdog/hardlockup: remove softlockup comment in touch_nmi_watchdog() Douglas Anderson
2023-05-27 1:41 ` Douglas Anderson
2023-05-30 14:42 ` Petr Mladek
2023-05-30 14:42 ` Petr Mladek
2023-05-27 1:41 ` [PATCH 06/10] watchdog/buddy: Cleanup how watchdog_buddy_check_hardlockup() is called Douglas Anderson
2023-05-27 1:41 ` Douglas Anderson
2023-05-30 14:56 ` Petr Mladek
2023-05-30 14:56 ` Petr Mladek
2023-05-27 1:41 ` [PATCH 07/10] watchdog/buddy: Don't copy the cpumask in watchdog_next_cpu() Douglas Anderson
2023-05-27 1:41 ` Douglas Anderson
2023-05-30 14:57 ` Petr Mladek
2023-05-30 14:57 ` Petr Mladek
2023-05-27 1:41 ` [PATCH 08/10] watchdog/buddy: Simplify the dependency for HARDLOCKUP_DETECTOR_PREFER_BUDDY Douglas Anderson
2023-05-27 1:41 ` Douglas Anderson
2023-05-30 14:58 ` Petr Mladek
2023-05-30 14:58 ` Petr Mladek
2023-05-27 1:41 ` [PATCH 09/10] watchdog/hardlockup: Move SMP barriers from common code to buddy code Douglas Anderson
2023-05-27 1:41 ` Douglas Anderson
2023-05-30 15:00 ` Petr Mladek
2023-05-30 15:00 ` Petr Mladek
2023-05-27 1:41 ` [PATCH 10/10] watchdog/hardlockup: Rename HAVE_HARDLOCKUP_DETECTOR_NON_ARCH to ..._PERF_OR_BUDDY Douglas Anderson
2023-05-27 1:41 ` Douglas Anderson
2023-06-01 13:03 ` Petr Mladek
2023-06-01 13:03 ` Petr Mladek
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZHYKSnLBU82fM1O2@alley \
--to=pmladek@suse.com \
--cc=akpm@linux-foundation.org \
--cc=christophe.leroy@csgroup.eu \
--cc=davem@davemloft.net \
--cc=dianders@chromium.org \
--cc=kgdb-bugreport@lists.sourceforge.net \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-perf-users@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
--cc=npiggin@gmail.com \
--cc=sparclinux@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.