linux-kernel - Re: [PATCH] pm: remove useless array definition in cpuidle

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Message-Id: <201111042328.43358.rjw@sisk.pl>
Date:	Fri, 4 Nov 2011 23:28:43 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	len.brown@...el.com, Arjan van de Ven <arjan@...ux.intel.com>
Cc:	Deepthi Dharwar <deepthi@...ux.vnet.ibm.com>,
	Robert Lee <rob.lee@...aro.org>, hpa@...ux.intel.com,
	daniel.lezcano@...aro.org, amit.kucheria@...aro.org,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	patches@...aro.org
Subject: Re: [PATCH] pm: remove useless array definition in cpuidle_structure

Len, Arjan,

On Friday, November 04, 2011, Deepthi Dharwar wrote:
> On Friday 04 November 2011 03:14 AM, Robert Lee wrote:
> > From: Daniel Lezcano <daniel.lezcano@...aro.org>
> > 
> > All the modules name are ro-data, it is never copied to the array.
> > 
> > eg.
> > 
> > static struct cpuidle_driver intel_idle_driver = {
> >         .name = "intel_idle",
> >         .owner = THIS_MODULE,
> > };
> > 
> > It safe to assign the pointer of this ro-data to a const char *.
> > By this way we save 12 bytes.
> > 
> > Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
> > Signed-off-by: Robert Lee <rob.lee@...aro.org>
> > ---
> >  include/linux/cpuidle.h |    4 ++--
> >  1 files changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
> > index b51629e..16f9dce 100644
> > --- a/include/linux/cpuidle.h
> > +++ b/include/linux/cpuidle.h
> > @@ -117,8 +117,8 @@ static inline int cpuidle_get_last_residency(struct cpuidle_device *dev)
> >   ****************************/
> > 
> >  struct cpuidle_driver {
> > -	char			name[CPUIDLE_NAME_LEN];
> > -	struct module 		*owner;
> > +	const char    *name;
> > +	struct module *owner;
> >  };
> > 
> >  #ifdef CONFIG_CPU_IDLE
> 
> This looks good, and makes it fool-proof by  not allowing one to tamper the name of the driver.
> Tested OK on x86 (both Intel idle and ACPI)
> 
> Tested-by: Deepthi Dharwar <deepthi@...ux.vnet.ibm.com>
> Reviewed-by: Deepthi Dharwar <deepthi@...ux.vnet.ibm.com>

This is simple enough for me to push it for 3.2, but I woulnd't like to
step on anyone's toes.  Please let me know what you think.

Rafael
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