Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <1612774577-55943-1-git-send-email-luojiaxing@huawei.com>
 <1612774577-55943-2-git-send-email-luojiaxing@huawei.com> <fab1e871-08e4-fc71-9dbf-9bcacf18e2e1@ti.com>
 <CAK8P3a0m4ocfLyJZ5wMxyKESYUJ5um5sb5MyAzC8ckCb6qAH5g@mail.gmail.com>
 <d5465b81-bb53-49ee-a556-40d208deb765@ti.com> <a61ef337fd1c4538a47fe855920f95d3@hisilicon.com>
In-Reply-To: <a61ef337fd1c4538a47fe855920f95d3@hisilicon.com>
From:   Arnd Bergmann <arnd@kernel.org>
Date:   Fri, 12 Feb 2021 10:45:12 +0100
Message-ID: <CAK8P3a3SHQNjF5ZpqHQweG7BQ52Xi1hQKDiMVKq4aNK_7VDw6w@mail.gmail.com>
Subject: Re: [Linuxarm] Re: [PATCH for next v1 1/2] gpio: omap: Replace
 raw_spin_lock_irqsave with raw_spin_lock in omap_gpio_irq_handler()
To:     "Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>
Cc:     Grygorii Strashko <grygorii.strashko@ti.com>,
        luojiaxing <luojiaxing@huawei.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Santosh Shilimkar <ssantosh@kernel.org>,
        Kevin Hilman <khilman@kernel.org>,
        "open list:GPIO SUBSYSTEM <linux-gpio@vger.kernel.org>,
        linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linuxarm@openeuler.org" <linuxarm@openeuler.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Fri, Feb 12, 2021 at 6:05 AM Song Bao Hua (Barry Song)
<song.bao.hua@hisilicon.com> wrote:
> > -----Original Message-----

> >
> > Note. there is also generic_handle_irq() call inside.
>
> So generic_handle_irq() is not safe to run in thread thus requires
> an interrupt-disabled environment to run? If so, I'd rather this
> irqsave moved into generic_handle_irq() rather than asking everyone
> calling it to do irqsave.

In a preempt-rt kernel, interrupts are run in task context, so they clearly
should not be called with interrupts disabled, that would defeat the
purpose of making them preemptible.

generic_handle_irq() does need to run with in_irq()==true though,
but this should be set by the caller of the gpiochip's handler, and
it is not set by raw_spin_lock_irqsave().

       Arnd