linux-kernel - Re: [PATCH v2 1/2] MIPS: SGI-IP27: micro-optimize arch_init

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Message-ID: <Zibs96v+uK/2uFT8@yury-ThinkPad>
Date: Mon, 22 Apr 2024 16:04:23 -0700
From: Yury Norov <yury.norov@...il.com>
To: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc: Florian Fainelli <f.fainelli@...il.com>, linux-mips@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] MIPS: SGI-IP27: micro-optimize arch_init_irq()

On Wed, Apr 17, 2024 at 01:10:52PM +0200, Thomas Bogendoerfer wrote:
> On Tue, Apr 16, 2024 at 10:37:10AM -0700, Yury Norov wrote:
> > The function sets adjusted groups of bits in hub_irq_map by using
> > for-loops. There's a bitmap_set() function dedicated to do this.
> > 
> > Because [0, CPU_CALL_B_IRQ] and [NI_BRDCAST_ERR_A, MSC_PANIC_INTR]
> > ranges belong to the same machine word, bitmap_set() would boil down
> > to an inline wrapper in both cases, avoiding generating a loop, with
> > the associate overhead. Effectively, it would be a compile-time:
> > 
> > 	*hub_irq_map = GENMASK() | GENMASK();
> > 
> > Signed-off-by: Yury Norov <yury.norov@...il.com>
> > ---
> >  arch/mips/sgi-ip27/ip27-irq.c | 8 ++------
> >  1 file changed, 2 insertions(+), 6 deletions(-)
> > 
> > diff --git a/arch/mips/sgi-ip27/ip27-irq.c b/arch/mips/sgi-ip27/ip27-irq.c
> > index 8f5299b269e7..d8acdf0439d2 100644
> > --- a/arch/mips/sgi-ip27/ip27-irq.c
> > +++ b/arch/mips/sgi-ip27/ip27-irq.c
> > @@ -277,7 +277,6 @@ void __init arch_init_irq(void)
> >  {
> >  	struct irq_domain *domain;
> >  	struct fwnode_handle *fn;
> > -	int i;
> 
> I've already applied your first version, so I need an incremental
> patch, which just removes the unused variable.

Sure, please find below.

>From ce447fe69092c48bb59a6c4cb08ee5f9080f0ad6 Mon Sep 17 00:00:00 2001
From: Yury Norov <yury.norov@...il.com>
Date: Mon, 22 Apr 2024 15:52:12 -0700
Subject: [PATCH] MIPS: SGI-IP27: fix -Wunused-variable in arch_init_irq()

Commit 40e20fbccfb722f21 (MIPS: SGI-IP27: micro-optimize arch_init_irq())
replaced a for-loop iteration with bitmap_set() calls, but didn't remove
an iteration variable.

Fixes: 40e20fbccfb722f21 (MIPS: SGI-IP27: micro-optimize arch_init_irq())
Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202404161933.izfqZ32k-lkp@intel.com/
Signed-off-by: Yury Norov <yury.norov@...il.com>
---
 arch/mips/sgi-ip27/ip27-irq.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/mips/sgi-ip27/ip27-irq.c b/arch/mips/sgi-ip27/ip27-irq.c
index dcb14a234b1c..d8acdf0439d2 100644
--- a/arch/mips/sgi-ip27/ip27-irq.c
+++ b/arch/mips/sgi-ip27/ip27-irq.c
@@ -277,7 +277,6 @@ void __init arch_init_irq(void)
 {
 	struct irq_domain *domain;
 	struct fwnode_handle *fn;
-	int i;
 
 	mips_cpu_irq_init();
 
-- 
2.40.1