linux-kernel - Re: [RFC! 10/13] Char: nozomi, fix tty_flip_buffer

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Date:	Sat, 10 Nov 2007 16:43:16 +0100
From:	Frank Seidel <fseidel@...e.de>
To:	Jiri Slaby <jirislaby@...il.com>
Cc:	linux-kernel@...r.kernel.org, Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [RFC! 10/13] Char: nozomi, fix tty_flip_buffer_push

On Samstag 10 November 2007 00:49:32, you (Jiri Slaby) wrote:
> Especially on this I would like to see feedback. Unlock and lock the
> spinlock just around the tty_flip_buffer_push would be much more easier, but
> won't it break anything?
> --
> nozomi, fix tty_flip_buffer_push
> 
> tty_flip_buffer_push call may deadlock when invoking it while holding
> spinlock used in e.g. throttle too. Nozomi sets low_latency tty and that
> means, that ldisc flush will be called immediately and it can call some
> nozomi functions back. Solve it by invoking tty_flip_buffer_push after
> releasing the spinlock.

IMHO its a brilliant idea to defer it this way to a safe place. I just
had to adapt the type of flip to "usigned long" (otherwise gcc spits
warnings around).
Eventhough i never ran in such a deadlock of course it looks much safer
now this way. I tested this patch and it seems to not break anything.

Applied without changes.

Thanks a lot,
Frank
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