linux-kernel - RE: [PATCH v2] Revert "base: arch_topology: fix section mismatch build warnings"

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Date:   Wed, 14 Mar 2018 04:27:42 +0000
From:   Gaku Inami <gaku.inami.xh@...esas.com>
To:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "dietmar.eggemann@....com" <dietmar.eggemann@....com>,
        "sudeep.holla@....com" <sudeep.holla@....com>,
        "juri.lelli@...hat.com" <juri.lelli@...hat.com>,
        "psodagud@...eaurora.org" <psodagud@...eaurora.org>
Subject: RE: [PATCH v2] Revert "base: arch_topology: fix section mismatch
 build warnings"

Hi,

Greg, would you review this? I confirmed it can be applied rebased on 4.16-rc5.

Regards
Inami

> -----Original Message-----
> From: Gaku Inami
> Sent: Tuesday, February 13, 2018 11:07 AM
> To: gregkh@...uxfoundation.org; linux-kernel@...r.kernel.org
> Cc: dietmar.eggemann@....com; sudeep.holla@....com; juri.lelli@...hat.com; psodagud@...eaurora.org; Gaku Inami
> <gaku.inami.xh@...esas.com>
> Subject: [PATCH v2] Revert "base: arch_topology: fix section mismatch build warnings"
> 
> This reverts commit 452562abb5b7 ("base: arch_topology: fix section
> mismatch build warnings"). It causes the notifier call hangs in some
> use-cases.
> 
> In some cases with using maxcpus, some of cpus are booted first and
> then the remaining cpus are booted. As an example, some users who want
> to realize fast boot up often use the following procedure.
> 
>   1) Define all CPUs on device tree (CA57x4 + CA53x4)
>   2) Add "maxcpus=4" in bootargs
>   3) Kernel boot up with CA57x4
>   4) After kernel boot up, CA53x4 is booted from user
> 
> When kernel init was finished, CPUFREQ_POLICY_NOTIFIER was not still
> unregisterd. This means that "__init init_cpu_capacity_callback()"
> will be called after kernel init sequence. To avoid this problem,
> it needs to remove __init{,data} annotations by reverting this commit.
> 
> Also, this commit was needed to fix kernel compile issue below.
> However, this issue was also fixed by another patch: commit 82d8ba717ccb
> ("arch_topology: Fix section miss match warning due to
> free_raw_capacity()") in v4.15 as well.
> Whereas commit 452562abb5b7 added all the missing __init annotations,
> commit 82d8ba717ccb removed it from free_raw_capacity().
> 
> WARNING: vmlinux.o(.text+0x548f24): Section mismatch in reference
> from the function init_cpu_capacity_callback() to the variable
> .init.text:$x
> The function init_cpu_capacity_callback() references
> the variable __init $x.
> This is often because init_cpu_capacity_callback lacks a __init
> annotation or the annotation of $x is wrong.
> 
> Fixes: 82d8ba717ccb ("arch_topology: Fix section miss match warning due
> to free_raw_capacity()")
> Signed-off-by: Gaku Inami <gaku.inami.xh@...esas.com>
> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@....com>
> Tested-by: Dietmar Eggemann <dietmar.eggemann@....com>
> Acked-by: Sudeep Holla <sudeep.holla@....com>
> ---
> 
> Changes from v1:
>  - rebase on v4.16-rc1
>  - add short tags for fixes.
>  - add tested-by, review-by and acked-by tags.
> 
>  drivers/base/arch_topology.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
> index 52ec517..e7cb0c6 100644
> --- a/drivers/base/arch_topology.c
> +++ b/drivers/base/arch_topology.c
> @@ -169,11 +169,11 @@ bool __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu)
>  }
> 
>  #ifdef CONFIG_CPU_FREQ
> -static cpumask_var_t cpus_to_visit __initdata;
> -static void __init parsing_done_workfn(struct work_struct *work);
> -static __initdata DECLARE_WORK(parsing_done_work, parsing_done_workfn);
> +static cpumask_var_t cpus_to_visit;
> +static void parsing_done_workfn(struct work_struct *work);
> +static DECLARE_WORK(parsing_done_work, parsing_done_workfn);
> 
> -static int __init
> +static int
>  init_cpu_capacity_callback(struct notifier_block *nb,
>  			   unsigned long val,
>  			   void *data)
> @@ -209,7 +209,7 @@ init_cpu_capacity_callback(struct notifier_block *nb,
>  	return 0;
>  }
> 
> -static struct notifier_block init_cpu_capacity_notifier __initdata = {
> +static struct notifier_block init_cpu_capacity_notifier = {
>  	.notifier_call = init_cpu_capacity_callback,
>  };
> 
> @@ -242,7 +242,7 @@ static int __init register_cpufreq_notifier(void)
>  }
>  core_initcall(register_cpufreq_notifier);
> 
> -static void __init parsing_done_workfn(struct work_struct *work)
> +static void parsing_done_workfn(struct work_struct *work)
>  {
>  	cpufreq_unregister_notifier(&init_cpu_capacity_notifier,
>  					 CPUFREQ_POLICY_NOTIFIER);
> --
> 2.7.4