linux-kernel - Re: lots of brief rcu stalls.

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: <1386210965.30493.84.camel@joe-AO722>
Date:	Wed, 04 Dec 2013 18:36:05 -0800
From:	Joe Perches <joe@...ches.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	paulmck@...ux.vnet.ibm.com, Dave Jones <davej@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Josh Triplett <josh@...edesktop.org>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: lots of brief rcu stalls.

On Wed, 2013-12-04 at 18:18 -0800, Eric Dumazet wrote:
> On Wed, 2013-12-04 at 16:16 -0800, Paul E. McKenney wrote:
> > +	    ULONG_CMP_GE(ACCESS_ONCE(jiffies), rdp->rsp->jiffies_resched)) {

perhaps time_before_eq

> jiffies should not need ACCESS_ONCE(), right ?
> 
> It is one of the few variables marked with volatile keyword.

It does seem redundant

$ git grep -n "ACCESS_ONCE(jiffies)"
kernel/rcu/torture.c:1354:      jiffies_snap = ACCESS_ONCE(jiffies);
kernel/rcu/torture.c:1363:              jiffies_snap = ACCESS_ONCE(jiffies);
kernel/rcu/tree.c:820:  unsigned long j = ACCESS_ONCE(jiffies);
kernel/rcu/tree.c:975:  j = ACCESS_ONCE(jiffies);
kernel/sched/core.c:2324:       unsigned long next, now = ACCESS_ONCE(jiffies);
kernel/sched/proc.c:536:        unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
kernel/sched/proc.c:558:        unsigned long curr_jiffies = ACCESS_ONCE(jiffies);


--
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/