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

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Date:   Thu, 1 Feb 2018 12:15:39 +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] of: cache phandle nodes to decrease cost of
 of_find_node_by_phandle()



On 2/1/2018 1:35 AM, frowand.list@...il.com wrote:
> From: Frank Rowand <frank.rowand@...y.com>

> +
> +static void of_populate_phandle_cache(void)
> +{
> +	unsigned long flags;
> +	phandle max_phandle;
> +	u32 nodes = 0;
> +	struct device_node *np;
> +
> +	if (phandle_cache)
> +		return;
> +
> +	max_phandle = live_tree_max_phandle();
> +
> +	raw_spin_lock_irqsave(&devtree_lock, flags);
> +
> +	for_each_of_allnodes(np)
> +		nodes++;
> +
> +	/* sanity cap for malformed tree */
> +	if (max_phandle > nodes)
> +		max_phandle = nodes;
Shouldn't we speak up about this in kernel log ? May be WARN_ON() ?

> +
> +	phandle_cache = kzalloc((max_phandle + 1) * sizeof(*phandle_cache),
> +				GFP_KERNEL);
kzalloc (might_sleep) in critical context will break.

Anyways, will fix this locally and share test results.

Thanks,
Chintan

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