linux-kernel - Re: [PATCH] procfs: do not confuse jiffies with cputime64

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:	Mon, 12 Dec 2011 09:22:13 +0000
From:	Arnd Bergmann <arnd@...db.de>
To:	Andreas Schwab <schwab@...ux-m68k.org>
Cc:	linux-kernel@...r.kernel.org, Michal Hocko <mhocko@...e.cz>,
	"Artem S. Tashkinov" <t.artem@...lcity.com>,
	Dave Jones <davej@...hat.com>,
	Alexey Dobriyan <adobriyan@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] procfs: do not confuse jiffies with cputime64_t

On Monday 12 December 2011, Andreas Schwab wrote:
> @@ -46,7 +46,7 @@ static cputime64_t get_iowait_time(int cpu)
>                 /* !NO_HZ so we can rely on cpustat.iowait */
>                 iowait = kstat_cpu(cpu).cpustat.iowait;
>         else
> -               iowait = nsecs_to_jiffies64(1000 * iowait_time);
> +               iowait = jiffies64_to_cputime64(nsecs_to_jiffies64(1000 * iowait_time));
>  
>         return iowait;

Hmm, shouldn't this be using nsecs_to_cputime64()? For some reason however, that function
is (incorrectly?) defined as 

include/asm-generic/cputime.h:#define nsecs_to_cputime64(__ct)  nsecs_to_jiffies64(__ct)

and only used in one place, in

kernel/sched.c: if (cputime64_gt(nsecs_to_cputime64(latest_ns), cpustat->irq))
kernel/sched.c: if (cputime64_gt(nsecs_to_cputime64(latest_ns), cpustat->softirq))

I'm not sure what the correct solution is, but I would assume that ia64 and powerpc
should fix their definitions of nsecs_to_cputime64() anyway.

	Arnd
--
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/