Re: [PATCH] msi: Only keep one msi_desc in each slab entry.

[ebiederm@xmission.com (Eric W. Biederman)]

Pekka J Enberg <penberg@cs.Helsinki.FI> writes:

> On Tue, 11 Jul 2006, Eric W. Biederman wrote:
>> Please look at what the code changes.
>> Please recognize how very bad the current code is behaving.
>
> Yes, there's plenty of slab confusion going on.
>
> On Tue, 11 Jul 2006, Eric W. Biederman wrote:
>> As for the rest sure go ahead and create a patch to address it
>> but that really is a separate issue and thus a separate patch.
>> 
>> I'm just trying to keep the kernel from calling BUG_ON the first
>> time a msi irq is allocated on a kernel with a maximum NR_CPUS
>> configuration, and from wasting memory the rest of the time.
>> 
>> Or you know how bad the msi code is when every patch to fix a major
>> issue is followed up comments on how to improve the code even further.
>
> Ok.

Looks good to me. 

> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
> ---
>
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index 36bc7c4..77b08ee 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -45,16 +45,11 @@ msi_register(struct msi_ops *ops)
>  	return 0;
>  }
>  
> -static void msi_cache_ctor(void *p, kmem_cache_t *cache, unsigned long flags)
> -{
> -	memset(p, 0, NR_IRQS * sizeof(struct msi_desc));
> -}
> -
>  static int msi_cache_init(void)
>  {
>  	msi_cachep = kmem_cache_create("msi_cache",
> -			NR_IRQS * sizeof(struct msi_desc),
> -		       	0, SLAB_HWCACHE_ALIGN, msi_cache_ctor, NULL);
> +			sizeof(struct msi_desc),
> +		       	0, SLAB_HWCACHE_ALIGN, NULL, NULL);
>  	if (!msi_cachep)
>  		return -ENOMEM;
>  
> @@ -402,11 +397,10 @@ static struct msi_desc* alloc_msi_entry(
>  {
>  	struct msi_desc *entry;
>  
> -	entry = kmem_cache_alloc(msi_cachep, SLAB_KERNEL);
> +	entry = kmem_cache_zalloc(msi_cachep, GFP_KERNEL);
>  	if (!entry)
>  		return NULL;
>  
> -	memset(entry, 0, sizeof(struct msi_desc));
>  	entry->link.tail = entry->link.head = 0;	/* single message */
>  	entry->dev = NULL;
>