linux-kernel - Re: [PATCH v3] of: cache phandle nodes to reduce cost of of_find_node_by

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Date:   Wed, 28 Feb 2018 18:57:08 +0530
From:   Chintan Pandya <cpandya@...eaurora.org>
To:     frowand.list@...il.com, Rob Herring <robh+dt@...nel.org>
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] of: cache phandle nodes to reduce cost of
 of_find_node_by_phandle()



On 2/15/2018 6:22 AM, frowand.list@...il.com wrote:

> +static void of_populate_phandle_cache(void)
> +{
> +	unsigned long flags;
> +	u32 cache_entries;
> +	struct device_node *np;
> +	u32 phandles = 0;
> +
> +	raw_spin_lock_irqsave(&devtree_lock, flags);
> +
> +	kfree(phandle_cache);
> +	phandle_cache = NULL;
> +
> +	for_each_of_allnodes(np)
> +		if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL)
> +			phandles++;
> +
> +	cache_entries = roundup_pow_of_two(phandles);
> +	phandle_cache_mask = cache_entries - 1;
> +
> +	phandle_cache = kcalloc(cache_entries, sizeof(*phandle_cache),
> +				GFP_ATOMIC);
> +

NULL check of phandle_cache would be good to have.

> +	for_each_of_allnodes(np)
> +		if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL)
> +			phandle_cache[np->phandle & phandle_cache_mask] = np;
> +
> +	raw_spin_unlock_irqrestore(&devtree_lock, flags);
> +}


Chintan
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