linux-kernel - Re: [PATCH] x86: fix IO APIC resource allocation error message

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Date:	Fri, 20 Mar 2009 20:23:23 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
Cc:	Alan Bartlett <ajb.stxsl@...glemail.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: fix IO APIC resource allocation error message


* Bartlomiej Zolnierkiewicz <bzolnier@...il.com> wrote:

> From: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
> Subject: [PATCH] x86: fix IO APIC resource allocation error message
> 
> Impact: fix incorrect error message
> 
> - IO APIC resource allocation error message contains one too many "be".
> 
> - Print the error message iff there are IO APICs in the system.
> 
> Cc: Alan Bartlett <ajb.stxsl@...glemail.com>
> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
> ---
> I've seen this error message for some time on my x86-32 laptop...
> 
>  arch/x86/kernel/io_apic.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> Index: b/arch/x86/kernel/io_apic.c
> ===================================================================
> --- a/arch/x86/kernel/io_apic.c
> +++ b/arch/x86/kernel/io_apic.c
> @@ -4150,9 +4150,9 @@ static int __init ioapic_insert_resource
>  	int i;
>  	struct resource *r = ioapic_resources;
>  
> -	if (!r) {
> +	if (!r && nr_ioapics > 0) {
>  		printk(KERN_ERR
> -		       "IO APIC resources could be not be allocated.\n");
> +		       "IO APIC resources couldn't be allocated.\n");
>  		return -1;
>  	}

looks good, but there's one weirdness:

so if nr_ioapics == 0 && !r we'll drop into this codepath:

        for (i = 0; i < nr_ioapics; i++) {
                insert_resource(&iomem_resource, r);
                r++;
        }

        return 0;

we survive the loop by luck, and then return 0 - which we'll survive 
too but still it's a bit unexpected and hence fragile.

So i think we should rather add a standalone:

	if (nr_ioapics > 0)
  		printk(KERN_ERR

check to the printk only. That wont affect the remaining code flow.

	Ingo
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