linux-kernel - Re: [PATCH, RFC] fasync() BKL pushdown

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20080620130905.6694a7be@bike.lwn.net>
Date:	Fri, 20 Jun 2008 13:09:05 -0600
From:	Jonathan Corbet <corbet@....net>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Al Viro <viro@...IV.linux.org.uk>
Subject: Re: [PATCH, RFC] fasync() BKL pushdown

On Fri, 20 Jun 2008 19:55:03 +0200
Andi Kleen <andi@...stfloor.org> wrote:

> Jonathan Corbet wrote:
> 
> > The majority of fasync() functions just call fasync_helper() with a
> > pointer to an fasync_struct reachable from the file structure.
> > Given that (1) the struct file will not go away while fasync() is
> > running, and (2) the VFS-level fasync() stuff is protected with the
> > Big Fasync Lock, I contend that these simple implementations have
> > no need for the BKL.  
> 
> Not necessarily true, they might require BKL still for fd live time
> issues.

Could you help me out a bit here?  I'm even slower than usual when it
comes to VFS stuff.  As far as I can tell, the given file cannot go
away during the call to fasync(), as sys_fcntl() holds a reference on
it.  Are you saying that something else can happen during that time?

Thanks,

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