linux-kernel - Re: [Bug fix PATCH v4] Reusing a resource structure allocated by bootmem

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Date:	Thu, 18 Apr 2013 17:28:55 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Cc:	akpm@...ux-foundation.org, linuxram@...ibm.com,
	rientjes@...gle.com, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [Bug fix PATCH v4] Reusing a resource structure allocated by
 bootmem

On Fri, 2013-04-19 at 08:33 +0900, Yasuaki Ishimatsu wrote:
 :
> >
> >> +static struct resource *get_resource(gfp_t flags)
> >> +{
> >> +	struct resource *res = NULL;
> >> +
> >> +	spin_lock(&bootmem_resource_lock);
> >> +	if (bootmem_resource.sibling) {
> >> +		res = bootmem_resource.sibling;
> >> +		bootmem_resource.sibling = res->sibling;
> >> +		memset(res, 0, sizeof(struct resource));
> >> +	}
> >> +	spin_unlock(&bootmem_resource_lock);
> >
> 
> > I prefer to keep memset() outside of the spin lock.
> >
> > spin_lock(&bootmem_resource_lock);
> > if (..) {
> > 	:
> > 	spin_unlock(&bootmem_resource_lock);
> > 	memset(res, 0, sizeof(struct resource));
> > } else {
> > 	spin_unlock(&bootmem_resource_lock);
> > 	res = kzalloc(sizeof(struct resource), flags);
> > }
> 
> Hmm. It is a little ugly. How about it?
> 
> spin_lock(&bootmem_resource_lock);
> if (bootmem_resource.sibling) {
> 	res = bootmem_resource.sibling;
> 	bootmem_resource.sibling = res->sibling;
> }
> spin_unlock(&bootmem_resource_lock);
> 
> if (res)
> 	memset(res, 0, sizeof(struct resource));
> else	
> 	res = kzalloc(sizeof(struct resource), flags);

Sounds good to me.

Thanks,
-Toshi


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