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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
Subject: Re: PROBLEM: Race condition in tty buffer's function flush_to_ldisc().
Date: Mon, 07 Nov 2011 16:20:15 +0400	[thread overview]
Message-ID: <4EB7CCFF.5090304@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.

I think so. But if add in flush_to_ldisc():

if (!test_and_set_bit(TTY_FLUSHING, &tty->flags)) {
	.....
} else
	prink...
In my syslog appear this prink on pty devices.

> 
> What cases does this occur ?
> 
> Also for the other patches do you have benchmarks yet ?
> 
> Alan
> 



  reply	other threads:[~2011-11-07 12:20 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 [this message]
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

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