From: Pavel Machek <pavel@suse.cz>
To: Paul Clements <paul.clements@steeleye.com>
Cc: kernel list <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@osdl.org>
Subject: Re: nbd: add locking to nbd_ioctl
Date: Fri, 16 Jan 2009 16:36:03 +0100 [thread overview]
Message-ID: <20090116153603.GD2022@elf.ucw.cz> (raw)
In-Reply-To: <4970A696.9070307@steeleye.com>
On Fri 2009-01-16 10:24:06, Paul Clements wrote:
> Pavel Machek wrote:
>> The code was written with "oh big kernel lock, please protect me from
>> all the evil" mentality: it does not locks its own data structures, it
>> just hopes that big kernel lock somehow helps.
>>
>> It does not. (My fault).
>>
>> So this uses tx_lock to protect data structures from concurrent use
>> between ioctl and worker threads.
>
> What is the particular problem that this fixes? I thought we had already
> been careful to take tx_lock where necessary to protect data structures.
> Perhaps there is something I missed?
for example lo->sock / lo->file are written to without holding any
lock in current code. (lo->xmit_timeout has similar problem, and other
fields, too).
I used tx_lock to protect those fields.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2009-01-16 15:34 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-16 11:55 nbd: add locking to nbd_ioctl Pavel Machek
2009-01-16 12:08 ` Pavel Machek
2009-01-16 12:29 ` Arnd Bergmann
2009-01-16 15:24 ` Paul Clements
2009-01-16 15:36 ` Pavel Machek [this message]
2009-01-16 16:28 ` Paul Clements
2009-01-19 9:54 ` Pavel Machek
2009-01-19 14:56 ` Paul Clements
2009-01-26 16:49 ` Pavel Machek
2009-01-26 17:01 ` Paul Clements
2009-01-26 17:32 ` Pavel Machek
-- strict thread matches above, loose matches on Subject: below --
2009-01-26 17:31 Pavel Machek
2009-01-29 1:14 ` Andrew Morton
2009-01-29 1:18 ` Andrew Morton
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