linux-kernel - Re: [PATCH 02/10] irqchip/gic-v3-its: Consolidate LPI_PENDBASE

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Date:   Mon, 24 Sep 2018 11:33:51 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     Marc Zyngier <marc.zyngier@....com>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Cc:     Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Jeremy Linton <jeremy.linton@....com>,
        Jeffrey Hugo <jhugo@...eaurora.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>
Subject: Re: [PATCH 02/10] irqchip/gic-v3-its: Consolidate LPI_PENDBASE_SZ
 usage

Hi Marc,

On 21/09/18 20:59, Marc Zyngier wrote:
> LPI_PENDING_SZ is always used in conjunction with a max(). Let's
> factor this in the definition of the macro, and simplify the rest
> of the code.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@....com>
> ---
>   drivers/irqchip/irq-gic-v3-its.c | 12 ++++--------
>   1 file changed, 4 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index c2df341ff6fa..ed6aab11e019 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -62,7 +62,7 @@ static u32 lpi_id_bits;
>    */
>   #define LPI_NRBITS		lpi_id_bits
>   #define LPI_PROPBASE_SZ		ALIGN(BIT(LPI_NRBITS), SZ_64K)
> -#define LPI_PENDBASE_SZ		ALIGN(BIT(LPI_NRBITS) / 8, SZ_64K)
> +#define LPI_PENDBASE_SZ		max_t(u32, SZ_64K, ALIGN(BIT(LPI_NRBITS) / 8, SZ_64K))

minor nit: The ALIGN() already aligns the given value up to the required
alignment. So, if the LPI_NRBITS is guaranteed to be non-zero,
we could simply drop the max_t().

Rest looks good to me.

Suzuki

>   
>   #define LPI_PROP_DEFAULT_PRIO	0xa0
>   
> @@ -1924,12 +1924,9 @@ static int its_alloc_collections(struct its_node *its)
>   static struct page *its_allocate_pending_table(gfp_t gfp_flags)
>   {
>   	struct page *pend_page;
> -	/*
> -	 * The pending pages have to be at least 64kB aligned,
> -	 * hence the 'max(LPI_PENDBASE_SZ, SZ_64K)' below.
> -	 */
> +
>   	pend_page = alloc_pages(gfp_flags | __GFP_ZERO,
> -				get_order(max_t(u32, LPI_PENDBASE_SZ, SZ_64K)));
> +				get_order(LPI_PENDBASE_SZ));
>   	if (!pend_page)
>   		return NULL;
>   
> @@ -1941,8 +1938,7 @@ static struct page *its_allocate_pending_table(gfp_t gfp_flags)
>   
>   static void its_free_pending_table(struct page *pt)
>   {
> -	free_pages((unsigned long)page_address(pt),
> -		   get_order(max_t(u32, LPI_PENDBASE_SZ, SZ_64K)));
> +	free_pages((unsigned long)page_address(pt), get_order(LPI_PENDBASE_SZ));
>   }
>   
>   static void its_cpu_init_lpis(void)
>