Re: [PATCH 1/3] irq_domain: remove "hint" when allocating irq numbers

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Wed, 2012-04-11 at 17:18 -0600, Grant Likely wrote:
> The 'hint' used to try and line up irq numbers with hw irq numbers is
> rather a hack and not very useful.  It also had some value when irq
> reverse mapping was lazy, and not done right at map time.  However, the
> lazy mapping is to be removed, so keeping around 'hint' isn't helpful
> anymore.  This patch removes it.

Please document that this also removes the support for irq_virq_count,
which breaks PS3, to be "fixed" by your patch 3/3 (you may want to
re-order the patches here) and that fixes an actual bug with mapping of
interrupts above NR_IRQS

Cheers,
Ben.

> v2: Rebase onto v3.4-rc2
> 
> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Milton Miller <miltonm@bga.com>
> Cc: Olof Johansson <olof@lixom.net>
> ---
>  kernel/irq/irqdomain.c |   23 ++++++-----------------
>  1 files changed, 6 insertions(+), 17 deletions(-)
> 
> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> index eb05e40..041710d 100644
> --- a/kernel/irq/irqdomain.c
> +++ b/kernel/irq/irqdomain.c
> @@ -4,6 +4,7 @@
>  #include <linux/irq.h>
>  #include <linux/irqdesc.h>
>  #include <linux/irqdomain.h>
> +#include <linux/irqnr.h>
>  #include <linux/module.h>
>  #include <linux/mutex.h>
>  #include <linux/of.h>
> @@ -350,7 +351,6 @@ unsigned int irq_create_direct_mapping(struct irq_domain *domain)
>  unsigned int irq_create_mapping(struct irq_domain *domain,
>  				irq_hw_number_t hwirq)
>  {
> -	unsigned int hint;
>  	int virq;
>  
>  	pr_debug("irq: irq_create_mapping(0x%p, 0x%lx)\n", domain, hwirq);
> @@ -378,14 +378,9 @@ unsigned int irq_create_mapping(struct irq_domain *domain,
>  		return irq_domain_legacy_revmap(domain, hwirq);
>  
>  	/* Allocate a virtual interrupt number */
> -	hint = hwirq % irq_virq_count;
> -	if (hint == 0)
> -		hint++;
> -	virq = irq_alloc_desc_from(hint, 0);
> -	if (virq <= 0)
> -		virq = irq_alloc_desc_from(1, 0);
> +	virq = irq_alloc_desc_from(1, 0);
>  	if (virq <= 0) {
> -		pr_debug("irq: -> virq allocation failed\n");
> +		pr_debug("irq: irq_desc allocation failed\n");
>  		return 0;
>  	}
>  
> @@ -516,7 +511,7 @@ unsigned int irq_find_mapping(struct irq_domain *domain,
>  			      irq_hw_number_t hwirq)
>  {
>  	unsigned int i;
> -	unsigned int hint = hwirq % irq_virq_count;
> +	struct irq_desc *desc;
>  
>  	/* Look for default domain if nececssary */
>  	if (domain == NULL)
> @@ -529,17 +524,11 @@ unsigned int irq_find_mapping(struct irq_domain *domain,
>  		return irq_domain_legacy_revmap(domain, hwirq);
>  
>  	/* Slow path does a linear search of the map */
> -	if (hint == 0)
> -		hint = 1;
> -	i = hint;
> -	do {
> +	for_each_irq_desc(i, desc)  {
>  		struct irq_data *data = irq_get_irq_data(i);
>  		if (data && (data->domain == domain) && (data->hwirq == hwirq))
>  			return i;
> -		i++;
> -		if (i >= irq_virq_count)
> -			i = 1;
> -	} while(i != hint);
> +	}
>  	return 0;
>  }
>  EXPORT_SYMBOL_GPL(irq_find_mapping);