linux-kernel - Re: [patch v3 6/7] x86/smp: Split sending INIT IPI out into a helper function

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Date:   Tue, 20 Jun 2023 11:29:06 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Mario Limonciello <mario.limonciello@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Tony Battersby <tonyb@...ernetics.com>,
        Ashok Raj <ashok.raj@...ux.intel.com>,
        Tony Luck <tony.luck@...el.com>,
        Arjan van de Veen <arjan@...ux.intel.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        Ashok Raj <ashok.raj@...el.com>
Subject: Re: [patch v3 6/7] x86/smp: Split sending INIT IPI out into a helper
 function

On Thu, Jun 15, 2023 at 10:33:58PM +0200, Thomas Gleixner wrote:
> Putting CPUs into INIT is a safer place during kexec() to park CPUs.
> 
> Split the INIT assert/deassert sequence out so it can be reused.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Reviewed-by: Ashok Raj <ashok.raj@...el.com>
> ---
> V2: Fix rebase screwup
> ---
>  arch/x86/kernel/smpboot.c |   49 ++++++++++++++++++----------------------------
>  1 file changed, 20 insertions(+), 29 deletions(-)
> 
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -853,47 +853,38 @@ wakeup_secondary_cpu_via_nmi(int apicid,
>  	return (send_status | accept_status);
>  }
>  
> -static int
> -wakeup_secondary_cpu_via_init(int phys_apicid, unsigned long start_eip)
> +static void send_init_sequence(int phys_apicid)
>  {
> -	unsigned long send_status = 0, accept_status = 0;
> -	int maxlvt, num_starts, j;
> -
> -	maxlvt = lapic_get_maxlvt();
> +	int maxlvt = lapic_get_maxlvt();

Whoops:

arch/x86/kernel/smpboot.c: In function ‘send_init_sequence’:
arch/x86/kernel/smpboot.c:860:9: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
  860 |         int maxlvt = lapic_get_maxlvt();
      |         ^~~

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette