Date: Wed, 4 Jun 2003 10:57:49 -0700 (PDT)
From: Linus Torvalds <torvalds@transmeta.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
cc: Christoph Hellwig <hch@infradead.org>, "P. Benie" <pjb1008@eng.cam.ac.uk>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] [2.5] Non-blocking write can block
In-Reply-To: <1054745247.9233.119.camel@dhcp22.swansea.linux.org.uk>
Message-ID: <Pine.LNX.4.44.0306041050250.14593-100000@home.transmeta.com>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1202
Lines: 30


On 4 Jun 2003, Alan Cox wrote:
>
> On Mer, 2003-06-04 at 15:35, Linus Torvalds wrote:
> > In general, we shouldn't do this, unless somebody can show an application 
> > where it really matters. Taking internal kernel locking into account for 
> > "blockingness" easily gets quite complicated, and there is seldom any real 
> > point to it.
> 
> Hanging shutdown is the obvious one. With 2.0/2.2 we had a similar
> problem and fixed it.

As I tried to point out, the current patch on the table doesn't actually
"fix" anything, in that it can break things even _worse_ than the current
situation.

A much better fix might well be to actually not allow over-long tty writes
at all, and thus avoid the "block out" thing at the source of the problem,
instead of trying to make programs who play nice be the ones that suffer.

If somebody does a 1MB write to a tty, do we actually have any reason to 
try to make it so damn atomic and not return early?

		Linus

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/