linux-kernel - Re: [PATCH 2/4] watchdog/softlockup: Use printk_cpu_sync_get

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Date: Fri, 22 Dec 2023 10:36:37 +0106
From: John Ogness <john.ogness@...utronix.de>
To: Douglas Anderson <dianders@...omium.org>, Andrew Morton
 <akpm@...ux-foundation.org>
Cc: Petr Mladek <pmladek@...e.com>, Li Zhe <lizhe.67@...edance.com>, Pingfan
 Liu <kernelfans@...il.com>, Lecopzer Chen <lecopzer.chen@...iatek.com>,
 Douglas Anderson <dianders@...omium.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] watchdog/softlockup: Use
 printk_cpu_sync_get_irqsave() to serialize reporting

On 2023-12-20, Douglas Anderson <dianders@...omium.org> wrote:
> Instead of introducing a spinlock, use printk_cpu_sync_get_irqsave()
> and printk_cpu_sync_put_irqrestore() to serialize softlockup
> reporting. Alone this doesn't have any real advantage over the
> spinlock, but this will allow us to use the same function in a future
> change to also serialize hardlockup crawls.

Thanks for this change. For me, this is the preferred workaround to
best-effort serialize a particular type of output. Hopefully one day we
will get to implementing printk contexts [0] [1] so that message blocks
can be inserted atomically.

> Signed-off-by: Douglas Anderson <dianders@...omium.org>

Reviewed-by: John Ogness <john.ogness@...utronix.de>

[0] https://lore.kernel.org/lkml/1299043680.4208.97.camel@Joe-Laptop
[1] https://lore.kernel.org/lkml/b17fc8afc8984fedb852921366190104@AcuMS.aculab.com