Re: [PATCH] fix sys cpumap for > 352 NR_CPUS

[Rusty Russell]

On Thu, 2004-06-03 at 09:11, Paul Jackson wrote:
> +	/*
> +	 * Hack alert:
> +	 * 1) This could overwrite a buffer w/o warning.  Someone should
> +	 *     pass us a buffer size (count) or use seq_file or something
> +	 *     to avoid buffer overrun risks.

Then just use -1UL as the arg to scnprintf, if you don't have a real
number.  That way the overflow will at least have a chance of detection
in the sysfs code, which I think it should check in
file.c:fill_read_buffer().  Greg?

> +	 * 2) This can return a count larger than the read size requested
> +	 *     by the user code - possibly confusing it.

That's sysfs' problem, not yours, and it handles it fine AFAICT.

> +	 * 3) Following hardcodes that mask scnprintf format requires 9
> +	 *     chars of output for each 32 bits of mask or fraction.

Yes.  Don't do that.

> +	 * 4) Following prints stale node_dev->cpumap value, instead of
> +	 *     evaluating afresh node_to_cpumask(node_dev->sysdev.id).
> +	 * 5) Why does struct node even has the field cpumap.  Won't it
> +	 *     just get stale, especially in the face of cpu hotplug?

Yes, that field should be removed.

Above all, by placing your questions inside a patch, you got results,
but please don't do this again.

Thanks,
Rusty.
-- 
Anyone who quotes me in their signature is an idiot -- Rusty Russell

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