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Subject: Re: [PATCH v3] of: cache phandle nodes to reduce cost of
 of_find_node_by_phandle()
To:     Chintan Pandya <cpandya@codeaurora.org>,
        Rob Herring <robh+dt@kernel.org>
Cc:     devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
References: <1518655979-10910-1-git-send-email-frowand.list@gmail.com>
 <ab87b605-6ec4-0b65-89ff-6232c89cb75f@codeaurora.org>
From:   Frank Rowand <frowand.list@gmail.com>
Message-ID: <22ed033d-fd35-7f06-39e3-075c500492b4@gmail.com>
Date:   Wed, 28 Feb 2018 10:22:39 -0800
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On 02/28/18 05:27, Chintan Pandya wrote:
> 
> 
> On 2/15/2018 6:22 AM, frowand.list@gmail.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.

Thanks for catching that.


>> +    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