linux-kernel - Re: [PATCH] X86: reboot-notify additions

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Message-ID: <87mylib004.fsf@basil.nowhere.org>
Date:	Thu, 19 Jun 2008 05:02:19 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Cliff Wickman <cpw@....com>
Cc:	mingo@...e.hu, tglx@...utronix.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] X86: reboot-notify additions

Cliff Wickman <cpw@....com> writes:

> From: Cliff Wickman <cpw@....com>
>
> X86 reboot-notify additions.

Doesn't seem x86 specific to me.

> @@ -1068,6 +1071,8 @@ void crash_kexec(struct pt_regs *regs)
>  	if (!locked) {
>  		if (kexec_crash_image) {
>  			struct pt_regs fixed_regs;
> +			blocking_notifier_call_chain(&reboot_notifier_list,
> +				SYS_INSANE, NULL);

But you don't really want to block during a crash, do you?

>  			crash_setup_regs(&fixed_regs, regs);
>  			crash_save_vmcoreinfo();
>  			machine_crash_shutdown(&fixed_regs);
> Index: linux/kernel/sys.c
> ===================================================================
> --- linux.orig/kernel/sys.c
> +++ linux/kernel/sys.c
> @@ -270,6 +270,7 @@ out_unlock:
>   */
>  void emergency_restart(void)
>  {
> +	blocking_notifier_call_chain(&reboot_notifier_list, SYS_INSANE, NULL);

Here neither.

In fact taking any locks here is dangerous because if you crash holding
such a lock the system will deadlock on panic.

-Andi
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