linux-kernel - Re: [PATCH 1/2] ftrace: add notrace to ARM sched

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Message-ID: <20090501233744.GF6404@nowhere>
Date:	Sat, 2 May 2009 01:37:45 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Tim Bird <tim.bird@...sony.com>
Cc:	linux kernel <linux-kernel@...r.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.arm.linux.org.uk>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ingo Molnar <mingo@...e.hu>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>,
	Russell King <rmk+kernel@....linux.org.uk>
Subject: Re: [PATCH 1/2]  ftrace: add notrace to ARM sched_clock routines

On Fri, May 01, 2009 at 03:30:05PM -0700, Tim Bird wrote:
> Add notrace attribute to sched_clock, to avoid
> recursion with ftrace function_graph tracing.
> 
> Signed-off-by: Tim Bird <tim.bird@...sony.com>
> ---
>  arch/arm/mach-mmp/time.c       |    2 +-
>  arch/arm/mach-pxa/time.c       |    2 +-
>  arch/arm/mach-realview/core.c  |    2 +-
>  arch/arm/mach-sa1100/generic.c |    2 +-
>  arch/arm/mach-versatile/core.c |    2 +-
>  arch/arm/plat-omap/common.c    |    4 ++--
>  6 files changed, 7 insertions(+), 7 deletions(-)
> 
> --- a/arch/arm/mach-mmp/time.c
> +++ b/arch/arm/mach-mmp/time.c
> @@ -72,7 +72,7 @@ static inline uint32_t timer_read(void)
>  	return __raw_readl(TIMERS_VIRT_BASE + TMR_CVWR(0));
>  }
> 
> -unsigned long long sched_clock(void)
> +unsigned long long notrace sched_clock(void)
>  {
>  	unsigned long long v = cnt32_to_63(timer_read());
>  	return (v * tcr2ns_scale) >> TCR2NS_SCALE_FACTOR;
> --- a/arch/arm/mach-pxa/time.c
> +++ b/arch/arm/mach-pxa/time.c
> @@ -51,7 +51,7 @@ static void __init set_oscr2ns_scale(uns
>  		oscr2ns_scale++;
>  }
> 
> -unsigned long long sched_clock(void)
> +unsigned long long notrace sched_clock(void)
>  {
>  	unsigned long long v = cnt32_to_63(OSCR);
>  	return (v * oscr2ns_scale) >> OSCR2NS_SCALE_FACTOR;
> --- a/arch/arm/mach-realview/core.c
> +++ b/arch/arm/mach-realview/core.c
> @@ -60,7 +60,7 @@ void __iomem *gic_cpu_base_addr;
>   * This is the RealView sched_clock implementation.  This has
>   * a resolution of 41.7ns, and a maximum value of about 179s.
>   */
> -unsigned long long sched_clock(void)
> +unsigned long long notrace sched_clock(void)
>  {
>  	unsigned long long v;
> 
> --- a/arch/arm/mach-sa1100/generic.c
> +++ b/arch/arm/mach-sa1100/generic.c
> @@ -131,7 +131,7 @@ EXPORT_SYMBOL(cpufreq_get);
>   *
>   *  ( * 1E9 / 3686400 => * 78125 / 288)
>   */
> -unsigned long long sched_clock(void)
> +unsigned long long notrace sched_clock(void)
>  {
>  	unsigned long long v = cnt32_to_63(OSCR);
> 
> --- a/arch/arm/mach-versatile/core.c
> +++ b/arch/arm/mach-versatile/core.c
> @@ -237,7 +237,7 @@ void __init versatile_map_io(void)
>   * long as there is always less than 89 seconds between successive
>   * calls to this function.
>   */
> -unsigned long long sched_clock(void)
> +unsigned long long notrace sched_clock(void)
>  {
>  	unsigned long long v = cnt32_to_63(readl(VERSATILE_REFCOUNTER));
> 
> --- a/arch/arm/plat-omap/common.c
> +++ b/arch/arm/plat-omap/common.c
> @@ -185,7 +185,7 @@ console_initcall(omap_add_serial_console
> 
>  #include <linux/clocksource.h>
> 
> -static cycle_t omap_32k_read(struct clocksource *cs)
> +static cycle_t notrace omap_32k_read(struct clocksource *cs)
>  {
>  	return omap_readl(TIMER_32K_SYNCHRONIZED);
>  }
> @@ -203,7 +203,7 @@ static struct clocksource clocksource_32
>   * Returns current time from boot in nsecs. It's OK for this to wrap
>   * around for now, as it's just a relative time stamp.
>   */
> -unsigned long long sched_clock(void)
> +unsigned long long notrace sched_clock(void)
>  {
>  	unsigned long long ret;


I've looked into all of these functions and they don't seem to call
anything that could be traced. I could have missed something though
but it looks good.

Acked-by: Frederic Weisbecker <fweisbec@...il.com>

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