Re: [PATCH] IB/usnic: Handle 0 counts in resource allocation

[Leon Romanovsky <leon-2ukJVAZIZ/Y@public.gmane.org>]

On Wed, Dec 09, 2015 at 10:42:19AM -0800, Nelson Escobar wrote:
> -	if (usnic_vnic_res_free_cnt(vnic, type) < cnt || cnt < 1 || !owner)
> +	if (usnic_vnic_res_free_cnt(vnic, type) < cnt || cnt < 0 || !owner)
Before this change you returned EINVAL if no free_cnt were available,
now you will continue. is this behaviour expected?

>  		return ERR_PTR(-EINVAL);
>  
>  	ret = kzalloc(sizeof(*ret), GFP_ATOMIC);
> @@ -247,26 +247,28 @@ usnic_vnic_get_resources(struct usnic_vnic *vnic, enum usnic_vnic_res_type type,
>  		return ERR_PTR(-ENOMEM);
>  	}
>  
> -	ret->res = kzalloc(sizeof(*(ret->res))*cnt, GFP_ATOMIC);
> -	if (!ret->res) {
> -		usnic_err("Failed to allocate resources for %s. Out of memory\n",
> -				usnic_vnic_pci_name(vnic));
> -		kfree(ret);
> -		return ERR_PTR(-ENOMEM);
> -	}
> +	if (cnt > 0) {
> +		ret->res = kcalloc(cnt, sizeof(*(ret->res)), GFP_ATOMIC);
> +		if (!ret->res) {
> +			usnic_err("Failed to allocate resources for %s. Out of memory\n",
> +					usnic_vnic_pci_name(vnic));
You don't need to print OOM messages, failure in memory allocation very hard to miss.
> +			kfree(ret);
> +			return ERR_PTR(-ENOMEM);
> +		}
>  
> -	spin_lock(&vnic->res_lock);
> -	src = &vnic->chunks[type];
> -	for (i = 0; i < src->cnt && ret->cnt < cnt; i++) {
> -		res = src->res[i];
> -		if (!res->owner) {
> -			src->free_cnt--;
> -			res->owner = owner;
> -			ret->res[ret->cnt++] = res;
> +		spin_lock(&vnic->res_lock);
> +		src = &vnic->chunks[type];
> +		for (i = 0; i < src->cnt && ret->cnt < cnt; i++) {
> +			res = src->res[i];
> +			if (!res->owner) {
> +				src->free_cnt--;
It will be negative, because of skip usnic_vnic_res_free_cnt check
before.
> +				res->owner = owner;
> +				ret->res[ret->cnt++] = res;
> +			}
>  		}
> -	}
>  
> -	spin_unlock(&vnic->res_lock);
> +		spin_unlock(&vnic->res_lock);
> +	}
>  	ret->type = type;
>  	ret->vnic = vnic;
>  	WARN_ON(ret->cnt != cnt);
> @@ -281,14 +283,16 @@ void usnic_vnic_put_resources(struct usnic_vnic_res_chunk *chunk)
>  	int i;
>  	struct usnic_vnic *vnic = chunk->vnic;
>  
> -	spin_lock(&vnic->res_lock);
> -	while ((i = --chunk->cnt) >= 0) {
> -		res = chunk->res[i];
> -		chunk->res[i] = NULL;
> -		res->owner = NULL;
> -		vnic->chunks[res->type].free_cnt++;
> +	if (chunk->cnt > 0) {
> +		spin_lock(&vnic->res_lock);
> +		while ((i = --chunk->cnt) >= 0) {
> +			res = chunk->res[i];
> +			chunk->res[i] = NULL;
> +			res->owner = NULL;
> +			vnic->chunks[res->type].free_cnt++;
> +		}
> +		spin_unlock(&vnic->res_lock);
>  	}
> -	spin_unlock(&vnic->res_lock);
>  
>  	kfree(chunk->res);
>  	kfree(chunk);
> -- 
> 2.4.3
> 
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