linux-kernel - Re: single bit flip detector.

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Date:	Wed, 02 Aug 2006 01:28:49 +0200
From:	Andreas Schwab <schwab@...e.de>
To:	Dave Jones <davej@...hat.com>
Cc:	Alexey Dobriyan <adobriyan@...il.com>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: single bit flip detector.

Dave Jones <davej@...hat.com> writes:

> diff --git a/mm/slab.c b/mm/slab.c
> index 21ba060..39f1183 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -1638,10 +1638,29 @@ static void poison_obj(struct kmem_cache
>  static void dump_line(char *data, int offset, int limit)
>  {
>  	int i;
> +	unsigned char total = 0, bad_count = 0, errors = 0;

No need to initialize errors here.

>  	printk(KERN_ERR "%03x:", offset);
> -	for (i = 0; i < limit; i++)
> +	for (i = 0; i < limit; i++) {
> +		if (data[offset + i] != POISON_FREE) {
> +			total += data[offset + i];
> +			bad_count++;
> +		}
>  		printk(" %02x", (unsigned char)data[offset + i]);
> +	}
>  	printk("\n");
> +
> +	if (bad_count == 1) {
> +		errors = total ^ POISON_FREE;
> +		if (errors && !(errors & (errors-1))) {
> +			printk (KERN_ERR "Single bit error detected. Probably bad RAM.\n");
> +#ifdef CONFIG_X86
> +			printk (KERN_ERR "Run memtest86+ or similar memory test tool.\n");
> +#else
> +			printk (KERN_ERR "Run a memory test tool.\n");
> +#endif
> +			return;

Useless return.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@...e.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
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