linux-kernel - Re: [tip:sched/core] sched/cpuacct: Split usage accounting into user_usage and sys

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:	Wed, 6 Apr 2016 09:50:00 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Zhao Lei <zhaolei@...fujitsu.com>
Cc:	'Ingo Molnar' <mingo@...nel.org>,
	'Srikar Dronamraju' <srikar@...ux.vnet.ibm.com>,
	tglx@...utronix.de, efault@....de, htejun@...il.com,
	linux-kernel@...r.kernel.org, tj@...nel.org,
	torvalds@...ux-foundation.org, yangds.fnst@...fujitsu.com,
	hpa@...or.com
Subject: Re: [tip:sched/core] sched/cpuacct: Split usage accounting into
 user_usage and sys_usage

On Wed, Apr 06, 2016 at 03:47:18PM +0800, Zhao Lei wrote:
> > If you change the above loop to something like:
> > 
> > 	for (ca = task_ca(tsk); ca; ca = parent_ca(ca)) {
> > 		if (WARN_ON_ONCE(!ca->cpuusage))
> > 			continue;
> > 		this_cpu_ptr(ca->cpuusage)->usages[index] += cputime;
> 
> Or s/ this_cpu_ptr/get_cpu_var to avoid preempt?

This is all called with rq->lock held, preemption is firmly disabled.