linux-kernel - Re: [PATCH] tty: serial: samsung_tty: remove spinlock flags in interrupt handlers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <YFB0OcBg3Vj555eA@hovoldconsulting.com>
Date:   Tue, 16 Mar 2021 10:02:49 +0100
From:   Johan Hovold <johan@...nel.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org, marcan@...can.st, arnd@...nel.org,
        Andy Shevchenko <andy.shevchenko@...il.com>
Subject: Re: [PATCH] tty: serial: samsung_tty: remove spinlock flags in
 interrupt handlers

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.

Johan