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From: Tejun Heo <tj@kernel.org>
To: Christoph Lameter <cl@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, Mel Gorman <mel@csn.ul.ie>,
	Pekka Enberg <penberg@cs.helsinki.fi>,
	Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
	Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [this_cpu_xx V7 7/8] Module handling: Use this_cpu_xx to dynamically allocate counters
Date: Tue, 15 Dec 2009 13:03:50 +0900	[thread overview]
Message-ID: <4B270AA6.3050307@kernel.org> (raw)
In-Reply-To: <20091214220342.473600725@quilx.com>

(Rusty Russell cc'd.)

On 12/15/2009 07:03 AM, Christoph Lameter wrote:
> @@ -479,15 +467,15 @@ static inline int try_module_get(struct 
>  	int ret = 1;
>  
>  	if (module) {
> -		unsigned int cpu = get_cpu();
>  		if (likely(module_is_live(module))) {
> -			local_inc(__module_ref_addr(module, cpu));
> +			preempt_disable();
> +			__this_cpu_inc(module->refptr->count);
>  			trace_module_get(module, _THIS_IP_,
> -				local_read(__module_ref_addr(module, cpu)));
> +				__this_cpu_read(module->refptr->count));
> +			preempt_enable();
>  		}
>  		else
>  			ret = 0;
> -		put_cpu();

I think you need preemption disabled while checking whether
module_is_live().  The state is protected by stop_machine or
synchronize_sched().

Thanks.

-- 
tejun

  reply	other threads:[~2009-12-15  4:02 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-12-14 22:03 [this_cpu_xx V7 0/8] Per cpu atomics in core allocators and cleanup Christoph Lameter
2009-12-14 22:03 ` [this_cpu_xx V7 1/8] this_cpu_ops: page allocator conversion Christoph Lameter
2009-12-15  3:53   ` Tejun Heo
2009-12-15 15:04     ` Christoph Lameter
2009-12-16  0:53       ` Tejun Heo
2009-12-16 14:55         ` Christoph Lameter
2009-12-17  0:23           ` Tejun Heo
2009-12-14 22:03 ` [this_cpu_xx V7 2/8] this_cpu ops: Remove pageset_notifier Christoph Lameter
2009-12-14 22:03 ` [this_cpu_xx V7 3/8] Use this_cpu operations in slub Christoph Lameter
2009-12-14 22:03 ` [this_cpu_xx V7 4/8] SLUB: Get rid of dynamic DMA kmalloc cache allocation Christoph Lameter
2009-12-14 22:03 ` [this_cpu_xx V7 5/8] this_cpu: Remove slub kmem_cache fields Christoph Lameter
2009-12-14 22:03 ` [this_cpu_xx V7 6/8] Make slub statistics use this_cpu_inc Christoph Lameter
2009-12-15  6:24   ` Eric Dumazet
2009-12-15 14:46     ` Christoph Lameter
2009-12-15 14:59       ` Eric Dumazet
2009-12-14 22:03 ` [this_cpu_xx V7 7/8] Module handling: Use this_cpu_xx to dynamically allocate counters Christoph Lameter
2009-12-15  4:03   ` Tejun Heo [this message]
2009-12-15 22:41     ` Rusty Russell
2009-12-16 16:10       ` Christoph Lameter
2009-12-17  0:25         ` Tejun Heo
2009-12-17  5:42           ` Rusty Russell
2009-12-14 22:03 ` [this_cpu_xx V7 8/8] Remove cpu_local_xx macros Christoph Lameter
2009-12-15  4:04   ` Tejun Heo
2009-12-15  6:37 ` [this_cpu_xx V7 0/8] Per cpu atomics in core allocators and cleanup Pekka Enberg
2009-12-15  6:47   ` Tejun Heo
2009-12-15 14:50     ` Christoph Lameter
2009-12-15 17:06 ` Mel Gorman
2009-12-16 14:44   ` Christoph Lameter
2009-12-16 21:36     ` Christoph Lameter
2009-12-15 17:43 ` Mathieu Desnoyers
2009-12-16  0:58   ` Tejun Heo
2009-12-16  1:40     ` Mathieu Desnoyers
2009-12-16  1:46       ` Tejun Heo
2009-12-17 13:39         ` Mathieu Desnoyers
2009-12-17 19:28           ` Christoph Lameter
2009-12-17 20:25             ` Mathieu Desnoyers
2009-12-17 20:43               ` Christoph Lameter
2009-12-18  0:13                 ` Mathieu Desnoyers
2009-12-18  0:27                   ` Christoph Lameter

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