From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Alexander Gordeev <lasaine@lvk.cs.msu.su>
Cc: linux-kernel@vger.kernel.org,
"Nikita V\. Youshchenko" <yoush@cs.msu.su>,
linuxpps@ml.enneenne.com,
Rodolfo Giometti <giometti@enneenne.com>,
Greg Kroah-Hartman <gregkh@suse.de>,
Arnd Bergmann <arnd@arndb.de>, Al Viro <viro@zeniv.linux.org.uk>,
Nick Piggin <npiggin@kernel.dk>,
"Alan \"I must be out of my tree\" Cox" <alan@linux.intel.com>,
Jason Wessel <jason.wessel@windriver.com>,
Philippe Langlais <philippe.langlais@stericsson.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCHv5 05/17] tty: don't allow ldisc dcd_change() after ldisc halt
Date: Wed, 24 Nov 2010 16:43:29 +0000 [thread overview]
Message-ID: <20101124164329.75368d71@lxorguk.ukuu.org.uk> (raw)
In-Reply-To: <48e935cac42ae455e2ef8fc45f7eef7631eece6b.1290599844.git.lasaine@lvk.cs.msu.su>
On Wed, 24 Nov 2010 19:15:43 +0300
Alexander Gordeev <lasaine@lvk.cs.msu.su> wrote:
> There was a possibility that uart_handle_dcd_change() could obtain a
> reference to ldisc while running in parallel with tty_set_ldisc() on
> different CPU but call dcd_change() operation after tty_ldisc_close()
> which is incorrect.
How can this occur ?
> + spin_lock_irqsave(&tty->dcd_change_lock, flags);
> +
> + ld = tty_ldisc_ref(tty);
What is the expecting lock ordering rule here ?
I don't see why this patch is needed. You've got an ldisc ref from
tty_ldisc_ref, until you drop that ldisc ref you are fine. If for some
reason that is not the case then there is a bug in the ldisc code.
Alan
next prev parent reply other threads:[~2010-11-24 16:45 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-24 16:15 [PATCHv5 00/17] pps: several fixes and improvements Alexander Gordeev
2010-11-24 16:15 ` [PATCHv5 01/17] pps: trivial fixes Alexander Gordeev
2010-11-24 16:15 ` [PATCHv5 02/17] pps: declare variables where they are used in switch Alexander Gordeev
2010-11-24 16:15 ` [PATCHv5 03/17] pps: fix race in PPS_FETCH handler Alexander Gordeev
2010-11-24 16:15 ` [PATCHv5 04/17] pps: unify timestamp gathering Alexander Gordeev
2010-11-24 16:15 ` [PATCHv5 05/17] tty: don't allow ldisc dcd_change() after ldisc halt Alexander Gordeev
2010-11-24 16:43 ` Alan Cox [this message]
2010-11-24 22:38 ` Alexander Gordeev
2010-11-24 22:36 ` Alan Cox
2010-11-25 13:30 ` Alexander Gordeev
2010-11-25 14:03 ` Alan Cox
2010-12-15 16:13 ` Alexander Gordeev
2010-11-24 16:15 ` [PATCHv5 06/17] pps: access pps device by direct pointer Alexander Gordeev
2010-12-16 15:52 ` Rodolfo Giometti
2010-12-16 21:58 ` Alexander Gordeev
2010-11-24 16:15 ` [PATCHv5 07/17] pps: convert printk/pr_* to dev_* Alexander Gordeev
2010-11-24 16:15 ` [PATCHv5 08/17] pps: move idr stuff to pps.c Alexander Gordeev
2010-12-16 15:53 ` Rodolfo Giometti
2010-11-24 16:15 ` [PATCHv5 09/17] pps: do not disable interrupts for idr operations Alexander Gordeev
2010-12-16 15:53 ` Rodolfo Giometti
2010-11-24 16:15 ` [PATCHv5 10/17] pps: use BUG_ON for kernel API safety checks Alexander Gordeev
2010-11-24 16:15 ` [PATCHv5 11/17] pps: simplify conditions a bit Alexander Gordeev
2010-11-24 16:15 ` [PATCHv5 12/17] pps: timestamp is always passed to dcd_change() Alexander Gordeev
2010-11-24 16:15 ` [PATCHv5 13/17] ntp: add hardpps implementation Alexander Gordeev
2010-11-24 16:15 ` [PATCHv5 14/17] pps: capture MONOTONIC_RAW timestamps as well Alexander Gordeev
2010-11-24 16:49 ` Thomas Gleixner
2010-11-25 9:55 ` Alexander Gordeev
2010-11-24 16:15 ` [PATCHv5 15/17] pps: add kernel consumer support Alexander Gordeev
2010-12-16 15:55 ` Rodolfo Giometti
2010-11-24 16:15 ` [PATCHv5 16/17] pps: add parallel port PPS client Alexander Gordeev
2010-12-16 15:58 ` Rodolfo Giometti
2010-11-24 16:15 ` [PATCHv5 17/17] pps: add parallel port PPS signal generator Alexander Gordeev
2010-12-16 16:02 ` Rodolfo Giometti
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