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List: linux-kernel
Subject: Re: [RFC][PATCH 17/18 v2] ftrace/cpuidle/x86: Mark functions that are RCU unsafe
From: "Paul E. McKenney" <paulmck () linux ! vnet ! ibm ! com>
Date: 2013-08-31 20:02:29
Message-ID: 20130831200229.GX3871 () linux ! vnet ! ibm ! com
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On Sat, Aug 31, 2013 at 01:11:34AM -0400, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
>
> Some callbacks of the function tracer use rcu_read_lock(). This means that
> there's places that can not be traced because RCU is not tracking the CPU
> for various reasons (like NO_HZ_FULL and coming back from userspace).
>
> Thes functions need to be marked so that callbacks that use RCU do not
> trace them.
>
> Cc: H. Peter Anvin <hpa@zytor.com>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> ---
> arch/x86/kernel/process.c | 2 ++
> drivers/cpuidle/cpuidle.c | 2 ++
> kernel/cpu/idle.c | 2 ++
> 3 files changed, 6 insertions(+)
>
> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
> index 83369e5..18739cd 100644
> --- a/arch/x86/kernel/process.c
> +++ b/arch/x86/kernel/process.c
> @@ -17,6 +17,7 @@
> #include <linux/stackprotector.h>
> #include <linux/tick.h>
> #include <linux/cpuidle.h>
> +#include <linux/ftrace.h>
> #include <trace/events/power.h>
> #include <linux/hw_breakpoint.h>
> #include <asm/cpu.h>
> @@ -316,6 +317,7 @@ void default_idle(void)
> #ifdef CONFIG_APM_MODULE
> EXPORT_SYMBOL(default_idle);
> #endif
> +FTRACE_UNSAFE_RCU(default_idle);
>
> #ifdef CONFIG_XEN
> bool xen_set_default_idle(void)
> diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
> index fdc432f..9515457 100644
> --- a/drivers/cpuidle/cpuidle.c
> +++ b/drivers/cpuidle/cpuidle.c
> @@ -19,6 +19,7 @@
> #include <linux/ktime.h>
> #include <linux/hrtimer.h>
> #include <linux/module.h>
> +#include <linux/ftrace.h>
> #include <trace/events/power.h>
>
> #include "cpuidle.h"
> @@ -168,6 +169,7 @@ int cpuidle_idle_call(void)
>
> return 0;
> }
> +FTRACE_UNSAFE_RCU(cpuidle_idle_call);
>
> /**
> * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
> diff --git a/kernel/cpu/idle.c b/kernel/cpu/idle.c
> index e695c0a..d9d290f 100644
> --- a/kernel/cpu/idle.c
> +++ b/kernel/cpu/idle.c
> @@ -5,6 +5,7 @@
> #include <linux/cpu.h>
> #include <linux/tick.h>
> #include <linux/mm.h>
> +#include <linux/ftrace.h>
> #include <linux/stackprotector.h>
>
> #include <asm/tlb.h>
> @@ -61,6 +62,7 @@ void __weak arch_cpu_idle(void)
> cpu_idle_force_poll = 1;
> local_irq_enable();
> }
> +FTRACE_UNSAFE_RCU(arch_cpu_idle);
>
> /*
> * Generic idle loop implementation
> --
> 1.7.10.4
>
>
--
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