commit 6fac4829ce0ef9b7f24369086ce5f0e9f38d37bc
author Frederic Weisbecker <fweisbec@gmail.com> Tue Nov 13 14:20:55 2012 +0100
committer Frederic Weisbecker <fweisbec@gmail.com> Sun Jan 27 19:23:31 2013 +0100
tree 44da712b66d778c2fd701f9c96b00e108530e1a9
parent 3f4724ea85b7d9055a9976fa8f30b471bdfbca93

cputime: Use accessors to read task cputime stats

This is in preparation for the full dynticks feature. While
remotely reading the cputime of a task running in a full
dynticks CPU, we'll need to do some extra-computation. This
way we can account the time it spent tickless in userspace
since its last cputime snapshot.

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>

kernel/posix-cpu-timers.c

diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index a278cad..165d476 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -155,11 +155,19 @@
 
 static inline cputime_t prof_ticks(struct task_struct *p)
 {
-	return p->utime + p->stime;
+	cputime_t utime, stime;
+
+	task_cputime(p, &utime, &stime);
+
+	return utime + stime;
 }
 static inline cputime_t virt_ticks(struct task_struct *p)
 {
-	return p->utime;
+	cputime_t utime;
+
+	task_cputime(p, &utime, NULL);
+
+	return utime;
 }
 
 static int
@@ -471,18 +479,23 @@
  */
 void posix_cpu_timers_exit(struct task_struct *tsk)
 {
+	cputime_t utime, stime;
+
 	add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
 						sizeof(unsigned long long));
+	task_cputime(tsk, &utime, &stime);
 	cleanup_timers(tsk->cpu_timers,
-		       tsk->utime, tsk->stime, tsk->se.sum_exec_runtime);
+		       utime, stime, tsk->se.sum_exec_runtime);
 
 }
 void posix_cpu_timers_exit_group(struct task_struct *tsk)
 {
 	struct signal_struct *const sig = tsk->signal;
+	cputime_t utime, stime;
 
+	task_cputime(tsk, &utime, &stime);
 	cleanup_timers(tsk->signal->cpu_timers,
-		       tsk->utime + sig->utime, tsk->stime + sig->stime,
+		       utime + sig->utime, stime + sig->stime,
 		       tsk->se.sum_exec_runtime + sig->sum_sched_runtime);
 }
 
@@ -1226,11 +1239,14 @@
 static inline int fastpath_timer_check(struct task_struct *tsk)
 {
 	struct signal_struct *sig;
+	cputime_t utime, stime;
+
+	task_cputime(tsk, &utime, &stime);
 
 	if (!task_cputime_zero(&tsk->cputime_expires)) {
 		struct task_cputime task_sample = {
-			.utime = tsk->utime,
-			.stime = tsk->stime,
+			.utime = utime,
+			.stime = stime,
 			.sum_exec_runtime = tsk->se.sum_exec_runtime
 		};