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From: Arnd Bergmann <arnd@arndb.de>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	John Kacur <jkacur@redhat.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Al Viro <viro@zeniv.linux.org.uk>, Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH 6/6] procfs: Kill the bkl in ioctl
Date: Thu, 1 Apr 2010 11:07:13 +0200	[thread overview]
Message-ID: <201004011107.13774.arnd@arndb.de> (raw)
In-Reply-To: <20100331225500.3ed98c1f@lxorguk.ukuu.org.uk>

On Wednesday 31 March 2010, Alan Cox wrote:
> > The recursive users that I've removed in my series are the block, tty,
> > input and sound subsystems, as well as the init code.
> 
> There are some very subtle recursive cases in the tty code - hangup
> triggered close and consoles being an absolute gem I've just had to debug
> in my lock removal bits so far...

Yes, I've seen some of them. What I meant above is that with
CONFIG_TTY_MUTEX=y, the TTY code no longer uses the BKL in a
nested way, and quite likely no either code does either.

The TTY code with my patch now has tty_lock() for all cases that
I concluded are never nested in another tty_lock, and tty_lock_nested()
for those I did not understand or that I know they are nested (the
latter type usually comes with a comment). The only difference
between the two is a WARN_ON(tty_locked()) in tty_lock, so we can
see where the analysis was wrong.

	Arnd

  reply	other threads:[~2010-04-01  9:07 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-30  6:20 [PATCH 0/6] Kill the bkl in procfs Frederic Weisbecker
2010-03-30  6:20 ` [PATCH 1/6] procfs: Kill BKL in llseek on proc base Frederic Weisbecker
2010-03-30  6:40   ` Alexey Dobriyan
2010-03-30  6:50     ` Frederic Weisbecker
2010-03-30  6:20 ` [PATCH 2/6] procfs: Use generic_file_llseek in /proc/kcore Frederic Weisbecker
2010-03-30 10:28   ` Arnd Bergmann
2010-03-30  6:20 ` [PATCH 3/6] procfs: Use generic_file_llseek in /proc/kmsg Frederic Weisbecker
2010-03-30 10:38   ` Arnd Bergmann
2010-03-30  6:20 ` [PATCH 4/6] procfs: Use generic_file_llseek in /proc/vmcore Frederic Weisbecker
2010-03-30 10:38   ` Arnd Bergmann
2010-03-30  6:20 ` [PATCH 5/6] procfs: Push down the bkl from ioctl Frederic Weisbecker
2010-03-30  6:31   ` Alexey Dobriyan
2010-03-30  7:02     ` Frederic Weisbecker
2010-04-09 14:45     ` [PATCH v2] " Frederic Weisbecker
2010-04-10 13:25       ` [PATCH v3] " Frederic Weisbecker
2010-05-17  1:23         ` [PATCH v4] " Frederic Weisbecker
2010-03-30 10:37   ` [PATCH 5/6] " Arnd Bergmann
2010-03-30 18:27     ` Frederic Weisbecker
2010-03-30 18:54       ` Arnd Bergmann
2010-03-30 19:21         ` Frederic Weisbecker
2010-03-30  6:20 ` [PATCH 6/6] procfs: Kill the bkl in ioctl Frederic Weisbecker
2010-03-30  6:38   ` Alexey Dobriyan
2010-03-30  7:07     ` Frederic Weisbecker
2010-03-30 10:33       ` Arnd Bergmann
2010-03-31 17:22         ` Frederic Weisbecker
2010-03-31 20:21           ` Arnd Bergmann
2010-03-31 21:04             ` Arnd Bergmann
2010-03-31 21:55               ` Alan Cox
2010-04-01  9:07                 ` Arnd Bergmann [this message]
2010-03-31 21:56               ` Frederic Weisbecker
2010-04-01 11:37                 ` Arnd Bergmann
2010-04-01 10:22               ` John Kacur
2010-03-31 21:41             ` Frederic Weisbecker
2010-04-01 12:42               ` Arnd Bergmann
2010-04-03 17:53                 ` Stefan Richter
2010-04-10 16:09                 ` Frederic Weisbecker
2010-04-12 15:05                   ` Arnd Bergmann
2010-04-10 16:14                 ` Frederic Weisbecker
2010-04-10 16:24                 ` Frederic Weisbecker
2010-04-01 11:39           ` Stefan Richter
2010-04-01 12:45             ` Arnd Bergmann
2010-04-10 15:28               ` Frederic Weisbecker
2010-04-11 13:03                 ` Christoph Hellwig
2010-04-12 17:34                   ` Arnd Bergmann
2010-04-12 21:53                     ` Frederic Weisbecker
2010-04-13  9:26                       ` Arnd Bergmann
2010-04-13 20:10                         ` Frederic Weisbecker
2010-04-13 18:03                     ` Christoph Hellwig
2010-04-10 13:27 ` [PATCH 0/6] Kill the bkl in procfs Frederic Weisbecker

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