linux-kernel - Re: workqueue deadlock

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]

Date:	Mon, 11 Dec 2006 11:15:45 +0530
From:	Srivatsa Vaddagiri <vatsa@...ibm.com>
To:	Andrew Morton <akpm@...l.org>
Cc:	Ingo Molnar <mingo@...e.hu>, Bjorn Helgaas <bjorn.helgaas@...com>,
	linux-kernel@...r.kernel.org, Myron Stowe <myron.stowe@...com>,
	Jens Axboe <axboe@...nel.dk>, Dipankar <dipankar@...ibm.com>,
	Gautham shenoy <ego@...ibm.com>
Subject: Re: workqueue deadlock

On Sun, Dec 10, 2006 at 04:16:00AM -0800, Andrew Morton wrote:
> One quite different way of addressing all of this is to stop using
> stop_machine_run() for hotplug synchronisation and switch to the swsusp
> freezer infrastructure: all kernel threads and user processes need to stop
> and park themselves in a known state before we allow the CPU to be removed.
> lock_cpu_hotplug() becomes a no-op.

Well ...you still need to provide some mechanism for stable access to
cpu_online_map in blocking functions (ex: do_event_scan_all_cpus). 
Freezing-tasks/Resuming-them-after-hotp-unplug is definitely not one of them 
(when they resume, online_map would have changed under their feet).

> Dunno if it'll work - I only just thought of it.  It sure would simplify
> things.

-- 
Regards,
vatsa
-
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/