From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Johan Hovold <johan@kernel.org>,
Finn Thain <fthain@telegraphics.com.au>,
Barry Song <song.bao.hua@hisilicon.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jirislaby@kernel.org>,
linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
Linux Samsung SOC <linux-samsung-soc@vger.kernel.org>,
"open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Hector Martin <marcan@marcan.st>, Arnd Bergmann <arnd@kernel.org>
Subject: Re: [PATCH] tty: serial: samsung_tty: remove spinlock flags in interrupt handlers
Date: Tue, 16 Mar 2021 11:40:57 +0200 [thread overview]
Message-ID: <CAHp75VfcbC63t_eZeBOA0NY28BtGBD0YyLR6nSNuKAnKhXTSzA@mail.gmail.com> (raw)
In-Reply-To: <YFB0OcBg3Vj555eA@hovoldconsulting.com>
On Tue, Mar 16, 2021 at 11:02 AM Johan Hovold <johan@kernel.org> wrote:
>
> On Mon, Mar 15, 2021 at 07:12:12PM +0100, Krzysztof Kozlowski wrote:
> > Since interrupt handler is called with disabled local interrupts, there
> > is no need to use the spinlock primitives disabling interrupts as well.
>
> This isn't generally true due to "threadirqs" and that can lead to
> deadlocks if the console code is called from hard irq context.
>
> Now, this is *not* the case for this particular driver since it doesn't
> even bother to take the port lock in console_write(). That should
> probably be fixed instead.
>
> See https://lore.kernel.org/r/X7kviiRwuxvPxC8O@localhost.
Finn, Barry, something to check I think?
--
With Best Regards,
Andy Shevchenko
WARNING: multiple messages have this Message-ID (diff)
From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Johan Hovold <johan@kernel.org>,
Finn Thain <fthain@telegraphics.com.au>,
Barry Song <song.bao.hua@hisilicon.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jirislaby@kernel.org>,
linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
Linux Samsung SOC <linux-samsung-soc@vger.kernel.org>,
"open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Hector Martin <marcan@marcan.st>, Arnd Bergmann <arnd@kernel.org>
Subject: Re: [PATCH] tty: serial: samsung_tty: remove spinlock flags in interrupt handlers
Date: Tue, 16 Mar 2021 11:40:57 +0200 [thread overview]
Message-ID: <CAHp75VfcbC63t_eZeBOA0NY28BtGBD0YyLR6nSNuKAnKhXTSzA@mail.gmail.com> (raw)
In-Reply-To: <YFB0OcBg3Vj555eA@hovoldconsulting.com>
On Tue, Mar 16, 2021 at 11:02 AM Johan Hovold <johan@kernel.org> wrote:
>
> On Mon, Mar 15, 2021 at 07:12:12PM +0100, Krzysztof Kozlowski wrote:
> > Since interrupt handler is called with disabled local interrupts, there
> > is no need to use the spinlock primitives disabling interrupts as well.
>
> This isn't generally true due to "threadirqs" and that can lead to
> deadlocks if the console code is called from hard irq context.
>
> Now, this is *not* the case for this particular driver since it doesn't
> even bother to take the port lock in console_write(). That should
> probably be fixed instead.
>
> See https://lore.kernel.org/r/X7kviiRwuxvPxC8O@localhost.
Finn, Barry, something to check I think?
--
With Best Regards,
Andy Shevchenko
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-03-16 9:42 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-15 18:12 [PATCH] tty: serial: samsung_tty: remove spinlock flags in interrupt handlers Krzysztof Kozlowski
2021-03-15 18:12 ` Krzysztof Kozlowski
2021-03-15 18:16 ` Andy Shevchenko
2021-03-15 18:16 ` Andy Shevchenko
2021-03-16 9:02 ` Johan Hovold
2021-03-16 9:02 ` Johan Hovold
2021-03-16 9:40 ` Andy Shevchenko [this message]
2021-03-16 9:40 ` Andy Shevchenko
2021-03-19 6:36 ` Song Bao Hua (Barry Song)
2021-03-19 6:36 ` Song Bao Hua (Barry Song)
2021-03-19 8:10 ` Johan Hovold
2021-03-19 8:10 ` Johan Hovold
2021-03-19 10:09 ` Andy Shevchenko
2021-03-19 10:09 ` Andy Shevchenko
2021-03-19 15:05 ` Johan Hovold
2021-03-19 15:05 ` Johan Hovold
2021-03-16 9:47 ` Krzysztof Kozlowski
2021-03-16 9:47 ` Krzysztof Kozlowski
2021-03-16 9:56 ` Johan Hovold
2021-03-16 9:56 ` Johan Hovold
2021-03-16 10:11 ` Krzysztof Kozlowski
2021-03-16 10:11 ` Krzysztof Kozlowski
2021-03-16 11:25 ` Johan Hovold
2021-03-16 11:25 ` Johan Hovold
2021-03-22 11:23 ` Johan Hovold
2021-03-22 11:23 ` Johan Hovold
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