linux-kernel - Re: [PATCH v3] auxdisplay: Remove in

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Message-ID: <20210216102856.dnaycukt3oqxoszp@linutronix.de>
Date:   Tue, 16 Feb 2021 11:28:56 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Willy Tarreau <w@....eu>
Subject: Re: [PATCH v3] auxdisplay: Remove in_interrupt() usage.

On 2021-02-16 10:32:15 [+0100], Miguel Ojeda wrote:
> Hi Sebastian,
Hi,

> On Sat, Feb 13, 2021 at 5:50 PM Sebastian Andrzej Siewior
> <bigeasy@...utronix.de> wrote:
> >
> > charlcd_write() is invoked as a VFS->write() callback and as such it is
> > always invoked from preemptible context and may sleep.
> 
> Can we put this sentence as a comment in the code, right before the
> call to cond_resched()?
> 
> > charlcd_puts() is invoked from register/unregister callback which is
> > preemtible. The reboot notifier callback is also invoked from
> 
> Same for this one.

Could we please avoid documenting the obvious? It is more or less common
knowledge that the write callback (like any other) is preemptible user
context (in which write occurs). The same is true for register/probe
functions. The non-preemptible / atomic is mostly the exception because
of the callback. Like from a timer or an interrupt.

> In addition, somehow the spelling fixes got lost from the previous version.
> 
> Same for the "code quotes": some have no quotes, others have `` or `'.
> No big deal, I can fix it on my side if needed, but just letting you
> know! :-)

I'm so sorry. I must have taken the wrong patch while doing the update.
My apologies. Once we sorted out the above, I will provide an update.

> Thanks!
> 
> Cheers,
> Miguel

Sebastian