linux-kernel - Re: [PATCH] mips: Fix using smp_processor

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Date:   Thu, 10 Aug 2017 09:57:40 +0200
From:   Marcin Nowakowski <marcin.nowakowski@...tec.com>
To:     <minyard@....org>, <linux-mips@...ux-mips.org>,
        <ralf@...ux-mips.org>, <linux-kernel@...r.kernel.org>
CC:     Corey Minyard <cminyard@...sta.com>
Subject: Re: [PATCH] mips: Fix using smp_processor_id() when preemptible

Hi Corey,

This has already been fixed here:
https://git.linux-mips.org/cgit/ralf/upstream-sfr.git/commit/?id=21da5332327b6d183bd93336ecf29c70bc609b7b

https://git.linux-mips.org/cgit/ralf/upstream-sfr.git/commit/?id=735302665c353d6756e7fa2a2cf41b039299f732

Marcin

On 09.08.2017 23:25, minyard@....org wrote:
> From: Corey Minyard <cminyard@...sta.com>
> 
> I was getting the following:
> 
> BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1
> caller is pcibios_set_cache_line_size+0x10/0x58
> 
> pcibios_set_cache_line_size() used current_cpu_data outside of
> an unpreemptible context.
> 
> Signed-off-by: Corey Minyard <cminyard@...sta.com>
> ---
>   arch/mips/pci/pci.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/mips/pci/pci.c b/arch/mips/pci/pci.c
> index bd67ac7..afd2f8a 100644
> --- a/arch/mips/pci/pci.c
> +++ b/arch/mips/pci/pci.c
> @@ -28,9 +28,11 @@ EXPORT_SYMBOL(PCIBIOS_MIN_MEM);
>   
>   static int __init pcibios_set_cache_line_size(void)
>   {
> -	struct cpuinfo_mips *c = &current_cpu_data;
> +	struct cpuinfo_mips *c;
>   	unsigned int lsize;
>   
> +	preempt_disable();
> +	c = &current_cpu_data;
>   	/*
>   	 * Set PCI cacheline size to that of the highest level in the
>   	 * cache hierarchy.
> @@ -38,6 +40,7 @@ static int __init pcibios_set_cache_line_size(void)
>   	lsize = c->dcache.linesz;
>   	lsize = c->scache.linesz ? : lsize;
>   	lsize = c->tcache.linesz ? : lsize;
> +	preempt_enable();
>   
>   	BUG_ON(!lsize);
>   
>