linux-kernel - Re: [PATCH -rt 1/4] x86_64: send NMI after nmi_show

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:	Mon, 28 Apr 2008 15:00:36 -0400 (EDT)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, linux-rt-users@...r.kernel.org
Subject: Re: [PATCH -rt 1/4] x86_64: send NMI after nmi_show_regs on



On Mon, 28 Apr 2008, Hiroshi Shimamoto wrote:
> diff --git a/arch/x86/kernel/nmi_64.c b/arch/x86/kernel/nmi_64.c
> index d187ab9..69cc737 100644
> --- a/arch/x86/kernel/nmi_64.c
> +++ b/arch/x86/kernel/nmi_64.c
> @@ -327,11 +327,11 @@ void nmi_show_all_regs(void)
>  	if (system_state == SYSTEM_BOOTING)
>  		return;
>
> -	smp_send_nmi_allbutself();
> -
>  	for_each_online_cpu(i)
>  		nmi_show_regs[i] = 1;

Hi Hiroshi,

I know this wasn't your code to begin with but, how does this function
exit?  I mean, we set an array where each index per online cpu is set to
one, then do an "nmi_allbutself", and then wait on those indexes to turn
zero, one at a time.  If we are CPU 0 here, we set that index to 1, then
enter the loop, and will block forever on this "while" loop below.

Am I missing something?

Thanks,

-- Steve



> +	smp_send_nmi_allbutself();
> +
>  	for_each_online_cpu(i) {
>  		while (nmi_show_regs[i] == 1)
>  			barrier();
> --
> 1.5.4.1
>
--
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/