linux-kernel - RE: [RFC 1/2] lib, Make gen_pool memory allocator lockless

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Date:	Thu, 10 Feb 2011 16:32:35 +0800
From:	Huang Ying <ying.huang@...el.com>
To:	"Luck, Tony" <tony.luck@...el.com>
Cc:	Len Brown <lenb@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andi Kleen <andi@...stfloor.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: RE: [RFC 1/2] lib, Make gen_pool memory allocator lockless

On Thu, 2011-02-10 at 03:03 +0800, Luck, Tony wrote:
> +static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set)
> +{
> +	unsigned long val, nval;
> +
> +	nval = *addr;
> +	do {
> +		val = nval;
> +		if (val & mask_to_set)
> +			return -EBUSY;
> +	} while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val);
> +
> +	return 0;
> +}
> 
> Spin loops like this should have a call to cpu_relax(), shouldn't they?

Thanks!  Sounds reasonable to me.  Will change it.

Best Regards,
Huang Ying


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