linux-kernel - Re: [PATCH] x86/mm: use WARN

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Message-ID: <0038691f-b247-f3b2-ee25-ac7b0e7b9aeb@kernel.org>
Date:   Mon, 26 Jul 2021 13:20:23 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     Jason Wang <wangborong@...rlc.com>
Cc:     dave.hansen@...ux.intel.com, peterz@...radead.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org,
        hpa@...or.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/mm: use WARN_ONCE

On 7/26/21 6:08 AM, Jason Wang wrote:
> printk + WARN_ON_ONCE can be just WARN_ONCE.
> 
> Signed-off-by: Jason Wang <wangborong@...rlc.com>
> ---
>  arch/x86/mm/ioremap.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
> index 60ade7dd71bd..3e57035ef9e3 100644
> --- a/arch/x86/mm/ioremap.c
> +++ b/arch/x86/mm/ioremap.c
> @@ -195,9 +195,8 @@ __ioremap_caller(resource_size_t phys_addr, unsigned long size,
>  		return NULL;
>  
>  	if (!phys_addr_valid(phys_addr)) {
> -		printk(KERN_WARNING "ioremap: invalid physical address %llx\n",
> -		       (unsigned long long)phys_addr);
> -		WARN_ON_ONCE(1);
> +		WARN_ONCE(1, "ioremap: invalid physical address %llx\n",
> +			  (unsigned long long)phys_addr);
>  		return NULL;
>  	}
>  
> 

This isn't a no-op change.  Before, it would KERN_WARNING once per event
and dump a trace once.  Now it will only print anything at all once.