Date: Tue, 22 Dec 2015 11:30:51 +0530
From: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, Chris Wilson <chris@chris-wilson.co.uk>,
        Ingo Molnar <mingo@kernel.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>
Subject: Re: [PATCH] Revert "kernel/stop_machine.c: remove CONFIG_SMP
 dependencies"
Message-ID: <20151222060051.GA5684@sudip-pc>
References: <1450433155-31615-1-git-send-email-sudipm.mukherjee@gmail.com>
 <20151218150753.6fa343f146682f17800c3b0a@linux-foundation.org>
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On Fri, Dec 18, 2015 at 03:07:53PM -0800, Andrew Morton wrote:
> On Fri, 18 Dec 2015 15:35:55 +0530 Sudip Mukherjee <sudipm.mukherjee@gmail.com> wrote:
> 
> > This reverts commit 64dab25b058c12f935794cb239089303bda7dbc1.
> > 
> > CONFIG_SMP dependency is needed for some arch like tile, tilegx and
> > m32r. They use stop_machine() but they donot have HOTPLUG_CPU and as a
> > result their builds are failing with "undefined symbol 'stop_machine'".
> 
> Thanks.  I had my &&'s and ||'s mixed up.   I did this:
> 
> --- a/kernel/stop_machine.c~kernel-stop_machinec-remove-config_smp-dependencies-fix
> +++ a/kernel/stop_machine.c
> @@ -531,8 +531,6 @@ static int __init cpu_stop_init(void)
>  }
>  early_initcall(cpu_stop_init);
>  
> -#ifdef CONFIG_HOTPLUG_CPU
> -
>  static int __stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus)
>  {
>  	struct multi_stop_data msdata = {
> @@ -630,5 +628,3 @@ int stop_machine_from_inactive_cpu(cpu_s
>  	mutex_unlock(&stop_cpus_mutex);
>  	return ret ?: done.ret;
>  }
> -
> -#endif	/* CONFIG_HOTPLUG_CPU */
> _
> 
> 
> Rationale:
> 
> stop_machine.o is only built when CONFIG_SMP=y so
> 
> #if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU)
> 
> always evaluates to true, so remove it.

Hi Andrew,
The error is still there. I guess you have been busy. :)

next-20151222 fails with the same error. You can see the m32r defconfig
at https://travis-ci.org/sudipm-mukherjee/parport/jobs/98258267

do you want me to send the patch to you for it?

regards
sudip
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