linux-kernel - Re: [PATCH] kdesu broken

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Message-ID: <87prblt7fv.fsf@devron.myhome.or.jp>
Date:	Tue, 28 Jul 2009 19:42:28 +0900
From:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Ray Lee <ray-lk@...rabbit.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] kdesu broken

Alan Cox <alan@...rguk.ukuu.org.uk> writes:

>> Just a quick hack though. Is this wrong/unpreferable way?
>> 
>> n_tty_read() checks the pending buffer and consume it before
>> input_available_p().
>
> That won't change the fact that the process could have exited.

Yes.

> You can fix the -ENXIO reporting that way (and it is basically what
> the EOFPENDING/EOF patch did), but the only way I can see to fix the
> assumption that the process exit means all the data is in the ldisc
> the other end ready to use is to actually to make the close() path
> block - but with some kind of limits to prevent deadlocks.

I thought, to check in n_tty_read() may guarantee that tty->buf (slave
guarantee to sent to tty->buf) is consumed by master side.

I hoped this tty->buf works as the pending data in ldisc.

Thanks.
-- 
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
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