linux-kernel - Re: [PATCH] powerpc/powernv/smp: fix a warning at CPU hotplug

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Message-ID: <875zk7hnbl.fsf@mpe.ellerman.id.au>
Date:   Tue, 29 Oct 2019 21:13:02 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Qian Cai <cai@....pw>
Cc:     peterz@...radead.org, paulmck@...ux.ibm.com, npiggin@...il.com,
        benh@...nel.crashing.org, paulus@...ba.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Qian Cai <cai@....pw>
Subject: Re: [PATCH] powerpc/powernv/smp: fix a warning at CPU hotplug

Qian Cai <cai@....pw> writes:
> The commit e78a7614f387 ("idle: Prevent late-arriving interrupts from
> disrupting offline") introduced a warning on powerpc with CPU hotplug,
>
> WARNING: CPU: 1 PID: 0 at arch/powerpc/platforms/powernv/smp.c:160
> pnv_smp_cpu_kill_self+0x5c/0x330
> Call Trace:
>  cpu_die+0x48/0x64
>  arch_cpu_idle_dead+0x30/0x50
>  do_idle+0x2e4/0x460
>  cpu_startup_entry+0x3c/0x40
>  start_secondary+0x7a8/0xa80
>  start_secondary_resume+0x10/0x14
>
> because it calls local_irq_disable() before arch_cpu_idle_dead().
>
> Fixes: e78a7614f387 ("idle: Prevent late-arriving interrupts from disrupting offline")
> Signed-off-by: Qian Cai <cai@....pw>
> ---
>  arch/powerpc/platforms/powernv/smp.c | 1 -
>  1 file changed, 1 deletion(-)

Thanks.

But Nick already sent a fix for this, I just need to review/test it and
get it merged, see:
  https://patchwork.ozlabs.org/patch/1181275/


cheers

> diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
> index fbd6e6b7bbf2..51f4e07b9168 100644
> --- a/arch/powerpc/platforms/powernv/smp.c
> +++ b/arch/powerpc/platforms/powernv/smp.c
> @@ -157,7 +157,6 @@ static void pnv_smp_cpu_kill_self(void)
>  	 * This hard disables local interurpts, ensuring we have no lazy
>  	 * irqs pending.
>  	 */
> -	WARN_ON(irqs_disabled());
>  	hard_irq_disable();
>  	WARN_ON(lazy_irq_pending());
>  
> -- 
> 1.8.3.1