linux-kernel - Re: [PATCH 01/12] blkcg: obtaining blkg should be enclosed inside rcu_read

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: <20120119155844.GE5198@google.com>
Date:	Thu, 19 Jan 2012 07:58:44 -0800
From:	Tejun Heo <tj@...nel.org>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	axboe@...nel.dk, ctalbott@...gle.com, rni@...gle.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/12] blkcg: obtaining blkg should be enclosed inside
 rcu_read_lock()

On Thu, Jan 19, 2012 at 10:54:45AM -0500, Vivek Goyal wrote:
> > No, no matter whatever synchronization scheme is in use, the code is
> > seriously screwed up if it's doing something like,
> > 
> > 	lock();
> > 	a = lookup();
> > 	unlock();
> > 	return a;
> > 
> > You should *NEVER* be doing that.
> 
> I guess ioc_lookup_icq() is doing something similar. We call it under
> queue lock. Take rcu lock inside for sanity of radix tree and then 
> release rcu lock and return icq.

Yeap, it is.  We should be using rcu_dereference_check() there too.

Thanks.

-- 
tejun
--
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/