linux-kernel - Re: [Linuxarm] [PATCH for next v1 0/2] gpio: few clean up patches to replace spin_lock_irqsave with spin

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Date:   Tue, 9 Feb 2021 17:24:28 +0800
From:   luojiaxing <luojiaxing@...wei.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
CC:     Linus Walleij <linus.walleij@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Grygorii Strashko <grygorii.strashko@...com>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        "Kevin Hilman" <khilman@...nel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        <linuxarm@...neuler.org>
Subject: Re: [Linuxarm] [PATCH for next v1 0/2] gpio: few clean up patches to
 replace spin_lock_irqsave with spin_lock

On 2021/2/8 21:28, Andy Shevchenko wrote:
> On Mon, Feb 8, 2021 at 11:11 AM luojiaxing <luojiaxing@...wei.com> wrote:
>> Sorry, my operation error causes a patch missing from this patch set. I
>> re-send the patch set. Please check the new one.
> What is the new one?! You have to give proper versioning and change
> log for your series.

sure, I will send a new one later, but let me answer your question first.

>
>> On 2021/2/8 16:56, Luo Jiaxing wrote:
>>> There is no need to use API with _irqsave in hard IRQ handler, So replace
>>> those with spin_lock.
> How do you know that another CPU in the system can't serve the
> following interrupt from the hardware at the same time?

Yes, I have some question before.

There are some similar discussion here,  please take a look, Song baohua 
explained it more professionally.

https://lore.kernel.org/lkml/e949a474a9284ac6951813bfc8b34945@hisilicon.com/

Here are some excerpts from the discussion:

I think the code disabling irq in hardIRQ is simply wrong.
Since this commit
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e58aa3d2d0cc
genirq: Run irq handlers with interrupts disabled

interrupt handlers are definitely running in a irq-disabled context
unless irq handlers enable them explicitly in the handler to permit
other interrupts.

Thanks

Jiaxing

>