linux-kernel - Re: [PATCH] v4 Teach RCU that idle task is not quiscent state at boot

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 for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 25 Feb 2009 17:00:24 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc:	linux-kernel@...r.kernel.org, vegard.nossum@...il.com,
	stable@...nel.org, akpm@...ux-foundation.org, npiggin@...e.de,
	penberg@...helsinki.fi
Subject: Re: [PATCH] v4 Teach RCU that idle task is not quiscent state at
	boot


* Paul E. McKenney <paulmck@...ux.vnet.ibm.com> wrote:

> +/* Internal to kernel, but needed by rcupreempt.h. */
> +extern int rcu_idle_cpu_truthful;

The name sucks a bit ;-) 'truthful' is an emotionally laden 
statement and distracts from the technical purpose when reading 
it ;)

Same for:

> +extern void rcu_idle_now_means_idle(void);

Also, i'm wondering, is there really no way to avoid this quirk. 
We almost got away without it for a long time.

This one:

>  void rcu_check_callbacks(int cpu, int user)
>  {
>  	if (user ||
> -	    (idle_cpu(cpu) && !in_softirq() &&
> -				hardirq_count() <= (1 << HARDIRQ_SHIFT))) {
> +	    (idle_cpu(cpu) && rcu_idle_cpu_truthful &&
> +	     !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) {

Is a hotpath called very often ...

	Ingo
--
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/