posix-cpu-timers: Rename thread_group_cputimer() and make it static

thread_group_cputimer() is a complete misnomer. The function does two things:

 - For arming process wide timers it makes sure that the atomic time
   storage is up to date. If no cpu timer is armed yet, then the atomic
   time storage is not updated by the scheduler for performance reasons.

   In that case a full summing up of all threads needs to be done and the
   update needs to be enabled.

- Samples the current time into the caller supplied storage.

Rename it to thread_group_start_cputime(), make it static and fixup the
callsite.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lkml.kernel.org/r/20190821192919.869350319@linutronix.de

diff --git a/include/linux/sched/cputime.h b/include/linux/sched/cputime.h
index 6de7b384d2be20df8f553b2a50f2bcfcd3bf79cf..2638fd0ab3f273643fcadb14a751d469a4b1f7c1 100644 (file)
--- a/include/linux/sched/cputime.h
+++ b/include/linux/sched/cputime.h
@@ -61,7 +61,6 @@ extern void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev,
  * Thread group CPU time accounting.
  */
 void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times);
-void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times);
 void thread_group_sample_cputime(struct task_struct *tsk, struct task_cputime *times);
 
 /*

diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index cb736787145bb4d315dd6b15babdd26760c5c401..def225ae069a69f3045c1bf4577e4edd588f5cd4 100644 (file)
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -253,7 +253,20 @@ void thread_group_sample_cputime(struct task_struct *tsk,
        sample_cputime_atomic(times, &cputimer->cputime_atomic);
 }
 
-void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
+/**
+ * thread_group_start_cputime - Start cputime and return a sample
+ * @tsk:       Task for which cputime needs to be started
+ * @iimes:     Storage for time samples
+ *
+ * The thread group cputime accouting is avoided when there are no posix
+ * CPU timers armed. Before starting a timer it's required to check whether
+ * the time accounting is active. If not, a full update of the atomic
+ * accounting store needs to be done and the accounting enabled.
+ *
+ * Updates @times with an uptodate sample of the thread group cputimes.
+ */
+static void
+thread_group_start_cputime(struct task_struct *tsk, struct task_cputime *times)
 {
        struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
        struct task_cputime sum;
@@ -536,7 +549,7 @@ static int cpu_timer_sample_group(const clockid_t which_clock,
 {
        struct task_cputime cputime;
 
-       thread_group_cputimer(p, &cputime);
+       thread_group_start_cputime(p, &cputime);
        switch (CPUCLOCK_WHICH(which_clock)) {
        default:
                return -EINVAL;