From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: "Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>
Cc: luojiaxing <luojiaxing@huawei.com>,
Linus Walleij <linus.walleij@linaro.org>,
Grygorii Strashko <grygorii.strashko@ti.com>,
Santosh Shilimkar <ssantosh@kernel.org>,
Kevin Hilman <khilman@kernel.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"linuxarm@openeuler.org" <linuxarm@openeuler.org>
Subject: Re: [Linuxarm] Re: [PATCH for next v1 0/2] gpio: few clean up patches to replace spin_lock_irqsave with spin_lock
Date: Wed, 10 Feb 2021 16:56:37 +0200 [thread overview]
Message-ID: <YCP0JeEUcoPp9B/H@smile.fi.intel.com> (raw)
In-Reply-To: <947bcef0d56a4d0c82729d6899394f4a@hisilicon.com>
On Wed, Feb 10, 2021 at 11:50:45AM +0000, Song Bao Hua (Barry Song) wrote:
> > -----Original Message-----
> > From: Andy Shevchenko [mailto:andy.shevchenko@gmail.com]
> > Sent: Wednesday, February 10, 2021 11:51 PM
> > On Wed, Feb 10, 2021 at 5:43 AM luojiaxing <luojiaxing@huawei.com> wrote:
> > > On 2021/2/9 17:42, Andy Shevchenko wrote:
...
> > > Between IRQ handler A and IRQ handle A, it's no need for a SLIS.
> >
> > Right, but it's not the case in the patches you provided.
>
> The code still holds spin_lock. So if two cpus call same IRQ handler,
> spin_lock makes them spin; and if interrupts are threaded, spin_lock
> makes two threads run the same handler one by one.
If you run on an SMP system and it happens that spin_lock_irqsave() just
immediately after spin_unlock(), you will get into the troubles. Am I mistaken?
I think this entire activity is a carefully crafted mine field for the future
syzcaller and fuzzers alike. I don't believe there are no side effects in a long
term on all possible systems and configurations (including forced threaded IRQ
handlers).
I would love to see a better explanation in the commit message of such patches
which makes it clear that there are *no* side effects.
For time being, NAK to the all patches of this kind.
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2021-02-10 14:57 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-08 8:56 [PATCH for next v1 0/2] gpio: few clean up patches to replace spin_lock_irqsave with spin_lock Luo Jiaxing
2021-02-08 8:56 ` [PATCH for next v1 1/2] gpio: omap: Replace raw_spin_lock_irqsave with raw_spin_lock in omap_gpio_irq_handler() Luo Jiaxing
2021-02-11 18:14 ` Grygorii Strashko
2021-02-11 19:39 ` Arnd Bergmann
2021-02-11 20:16 ` Grygorii Strashko
2021-02-12 5:05 ` [Linuxarm] " Song Bao Hua (Barry Song)
2021-02-12 9:45 ` Arnd Bergmann
2021-02-12 10:25 ` Song Bao Hua (Barry Song)
2021-02-12 10:27 ` Grygorii Strashko
2021-02-12 10:42 ` Song Bao Hua (Barry Song)
2021-02-12 10:57 ` Andy Shevchenko
2021-02-12 11:29 ` Song Bao Hua (Barry Song)
2021-02-12 11:53 ` Grygorii Strashko
2021-02-12 13:12 ` Song Bao Hua (Barry Song)
2021-02-12 14:08 ` Grygorii Strashko
2021-02-12 20:06 ` Song Bao Hua (Barry Song)
2021-02-12 20:23 ` Arnd Bergmann
2021-02-12 20:49 ` Song Bao Hua (Barry Song)
2021-02-12 10:59 ` Arnd Bergmann
2021-02-12 11:35 ` Andy Shevchenko
2021-02-08 9:11 ` [Linuxarm] [PATCH for next v1 0/2] gpio: few clean up patches to replace spin_lock_irqsave with spin_lock luojiaxing
2021-02-08 13:28 ` Andy Shevchenko
2021-02-09 9:24 ` luojiaxing
2021-02-09 9:42 ` Andy Shevchenko
2021-02-10 3:43 ` luojiaxing
2021-02-10 10:50 ` Andy Shevchenko
2021-02-10 11:50 ` [Linuxarm] " Song Bao Hua (Barry Song)
2021-02-10 14:56 ` Andy Shevchenko [this message]
2021-02-10 20:42 ` Song Bao Hua (Barry Song)
2021-02-11 9:58 ` Andy Shevchenko
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