linux-kernel - Re: [PATCH 32/35] clockevents: Fix cpu down race for hrtimer based broadcasting

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: <54E58A61.60200@linux.vnet.ibm.com>
Date:	Thu, 19 Feb 2015 12:31:53 +0530
From:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	linux-kernel@...r.kernel.org, mingo@...nel.org, rjw@...ysocki.net,
	tglx@...utronix.de
Subject: Re: [PATCH 32/35] clockevents: Fix cpu down race for hrtimer based
 broadcasting

On 02/18/2015 06:36 PM, Peter Zijlstra wrote:
> On Wed, Feb 18, 2015 at 08:40:52AM +0530, Preeti U Murthy wrote:
>>
>> Look at the changelog, 
> 
> Heh, yah, clearly I tl;dr'd that. Indeed.
> 
>> it explains why tick_takeover must be called
>> *before* __cpu_die(). 
> 
> Since you reported this, can you test if things work if you move that
> function call to before __cpu_die() ?

Yes it does. I had tested and posted out a patch to fix the issue
here:https://lkml.org/lkml/2015/1/30/821. I see now that tglx proposes
to get rid of "taking over" tick duties going forward, rather "handing
over" tick duties would be better. So the patch in the above link would
not be acceptable. But minus the taking over of the do_timer, the cpu
doing the hotplug takes over broadcast duty before __cpu_die() in this
patch. This design works.

Regards
Preeti U Murthy
> 
> I _think_ it should be fine, but what do I know ;-)
> 

--
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/