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context_tracking: Export context state for generic vtime 

Export the context state: whether we run in user / kernel
from the context tracking subsystem point of view.

This is going to be used by the generic virtual cputime
accounting subsystem that is needed to implement the full
dynticks.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Frederic Weisbecker 2013-01-07 18:12:14 +01:00
parent 7d1f9aeff1
commit 95a79fd458
2 changed files with 29 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
include/linux/context_tracking.h
View File

@ -3,12 +3,40 @@
#ifdef CONFIG_CONTEXT_TRACKING
#include <linux/sched.h>
#include <linux/percpu.h>
struct context_tracking {
/*
* When active is false, probes are unset in order
* to minimize overhead: TIF flags are cleared
* and calls to user_enter/exit are ignored. This
* may be further optimized using static keys.
*/
bool active;
enum {
IN_KERNEL = 0,
IN_USER,
} state;
};
DECLARE_PER_CPU(struct context_tracking, context_tracking);
static inline bool context_tracking_in_user(void)
{
return __this_cpu_read(context_tracking.state) == IN_USER;
}
static inline bool context_tracking_active(void)
{
return __this_cpu_read(context_tracking.active);
}
extern void user_enter(void);
extern void user_exit(void);
extern void context_tracking_task_switch(struct task_struct *prev,
struct task_struct *next);
#else
static inline bool context_tracking_in_user(void) { return false; }
static inline void user_enter(void) { }
static inline void user_exit(void) { }
static inline void context_tracking_task_switch(struct task_struct *prev,

16
kernel/context_tracking.c
View File

@ -1,24 +1,10 @@
#include <linux/context_tracking.h>
#include <linux/rcupdate.h>
#include <linux/sched.h>
#include <linux/percpu.h>
#include <linux/hardirq.h>
struct context_tracking {
/*
* When active is false, hooks are not set to
* minimize overhead: TIF flags are cleared
* and calls to user_enter/exit are ignored. This
* may be further optimized using static keys.
*/
bool active;
enum {
IN_KERNEL = 0,
IN_USER,
} state;
};
static DEFINE_PER_CPU(struct context_tracking, context_tracking) = {
DEFINE_PER_CPU(struct context_tracking, context_tracking) = {
#ifdef CONFIG_CONTEXT_TRACKING_FORCE
.active = true,
#endif