From: Ilya Zykov <ilya@ilyx.ru>
To: Alan Cox <alan@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>,
linux-kernel@vger.kernel.org, Ilya Zykov <ilya@ilyx.ru>
Subject: Re: PROBLEM: Race condition in tty buffer's function flush_to_ldisc().
Date: Mon, 07 Nov 2011 16:35:48 +0400 [thread overview]
Message-ID: <4EB7D0A4.405@ilyx.ru> (raw)
In-Reply-To: <20111107115802.23201d45@bob.linux.org.uk>
Alan Cox wrote:
> On Mon, 07 Nov 2011 15:14:34 +0400
> Ilya Zykov <ilya@ilyx.ru> wrote:
>
>> Function flush_to_ldisc() call disc->ops->receive_buf(),
>> without tty->buf.lock and with TTY_FLUSHING bit set.
>
> flush_to_ldisc is single threaded for a given tty. If you fail to
> ensure that is the case everything breaks.
Why we need: "if (!test_and_set_bit(TTY_FLUSHING, &tty->flags)) {"
if flush_to_ldisc is single threaded?
we can: set_bit(TTY_FLUSHING, &tty->flags)
without if() at all.
>
> What cases does this occur ?
>
> Also for the other patches do you have benchmarks yet ?
>
> Alan
>
prev parent reply other threads:[~2011-11-07 12:36 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-07 11:14 PROBLEM: Race condition in tty buffer's function flush_to_ldisc() Ilya Zykov
2011-11-07 11:58 ` Alan Cox
2011-11-07 12:20 ` Ilya Zykov
2011-11-07 13:06 ` Alan Cox
2011-11-07 13:44 ` Ilya Zykov
2011-11-07 14:50 ` Alan Cox
2011-11-07 14:52 ` Ilya Zykov
2011-11-07 18:26 ` Ilya Zykov
2011-11-07 18:39 ` Alan Cox
2011-11-07 18:41 ` Alan Cox
2011-11-07 12:35 ` Ilya Zykov [this message]
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