linux-kernel - Re: [PATCH] x86_64: fix delayed signals

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Date:	Sun, 13 Jul 2008 14:34:16 +0200
From:	Denys Vlasenko <vda.linux@...glemail.com>
To:	Oleg Nesterov <oleg@...sign.ru>
Cc:	T?r?k Edwin <edwintorok@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	Roland McGrath <roland@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Elias Oltmanns <eo@...ensachen.de>,
	Arjan van de Ven <arjan@...radead.org>
Subject: Re: [PATCH] x86_64: fix delayed signals

On Sunday 13 July 2008 12:46, Oleg Nesterov wrote:
> On 07/12, Denys Vlasenko wrote:
> >
> > On Saturday 12 July 2008 22:26, T?r?k Edwin wrote:
> > > A bit off-topic, but something I noticed during the tests:
> > > In my original test I have rm-ed the files right after launching dd in
> > > the background, yet it still continued to write to the disk.
> > > I can understand that if the file is opened O_RDWR, you might seek back
> > > and read what you wrote, so Linux needs to actually do the write,
> > > but why does it insist on writing to the disk, on a file opened with
> > > O_WRONLY, after the file itself got unlinked?
> >
> > Because process can do
> >
> > fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_RDWR)
> 
> Is it?
> 
> SETFL_MASK doesn't have O_RDWR, and in any case setfl() changes ->f_flags,
> not ->f_mode.

Just tested it and you are right.

I distinctly remember seeing such code somewhere. Interesting.
Now I wonder whether it was a bug, or those were not file descriptors,
but sockets?...
--
vda
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