linux-kernel - Re: [PATCH v7 3/5] irqdomain: Add irq_domain_{push,pop}

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Date:   Tue, 15 Aug 2017 20:02:02 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     David Daney <ddaney@...iumnetworks.com>
Cc:     David Daney <david.daney@...ium.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Alexandre Courbot <gnurou@...il.com>,
        Mark Rutland <mark.rutland@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        <linux-gpio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 3/5] irqdomain: Add irq_domain_{push,pop}_irq() functions.

On Tue, Aug 15 2017 at 11:00:19 am BST, David Daney <ddaney@...iumnetworks.com> wrote:
> On 08/15/2017 06:50 AM, Marc Zyngier wrote:
>> Hi David,
>>
>> On 09/08/17 23:51, David Daney wrote:
> [...]
>>> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
>>> index f1f2514..629f770 100644
>>> --- a/kernel/irq/irqdomain.c
>>> +++ b/kernel/irq/irqdomain.c
>>> @@ -1448,6 +1448,184 @@ int __irq_domain_alloc_irqs(struct
> irq_domain *domain, int irq_base,
>>>   	return ret;
>>>   }
>>>   +/* The irq_data was moved, fix the revmap to refer to the new
>>> location */
>>> +static void irq_domain_fix_revmap(struct irq_data *d)
>>> +{
>>> +	void **slot;
>>> +
>>> +	if (d->hwirq < d->domain->revmap_size)
>>> +		return; /* Not using radix tree. */
>>> +
>>> +	/* Fix up the revmap. */
>>> +	mutex_lock(&revmap_trees_mutex);
>>> +	slot = radix_tree_lookup_slot(&d->domain->revmap_tree, d->hwirq);
>>> +	if (slot)
>>> +		radix_tree_replace_slot(&d->domain->revmap_tree, slot, d);
>>
>> radix_tree_replace_slot already deals with non-existing entries, so the
>> initial radix_tree_lookup_slot call is superfluous.
>
> This comment I don't understand.  To replace an element in the tree,
> you must know the slot.  I see no alternative to calling
> radix_tree_lookup_slot().  If I am mistaken, it would be helpful to
> know in a little more detail how you think it should be done.

Nah, you're right. I'm just grossly mistaken. Ignore this.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny.