linux-kernel - [Query]: sched/fair: prio_changed

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-next>] [day] [month] [year] [list]

Date:	Wed, 7 Nov 2012 13:19:01 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	mingo@...hat.com, Peter Zijlstra <peterz@...radead.org>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Lists linaro-dev <linaro-dev@...ts.linaro.org>,
	PDSW-power-team <pdsw-power-team@....com>
Subject: [Query]: sched/fair: prio_changed_fair()

Hi Ingo/Peter,

I am trying to understand the complex scheduler code and just found
something incorrect (maybe i am not reading it well):

File: kernel/sched/fair.c

static void
prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
{
	if (!p->se.on_rq)
		return;

	/*
	 * Reschedule if we are currently running on this runqueue and
	 * our priority decreased, or if we are not currently running on
	 * this runqueue and our priority is higher than the current's
	 */
	if (rq->curr == p) {
		if (p->prio > oldprio)
			resched_task(rq->curr);
	} else
		check_preempt_curr(rq, p, 0);
}


Comment says that we must mark the task to be rescheduled, if we
are currently running and our priority has decreased. But in code we
are checking (p->prio > oldprio). i.e. reschedule if we were currently
running and our priority increased.

Sorry if i am wrong :(

--
viresh
--
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/