posix-cpu-timers: Simplify sample functions

All callers hand in a valdiated clock id. Remove the return value which was
unchecked in most places anyway.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lkml.kernel.org/r/20190821192920.430475832@linutronix.de

kernel/time/posix-cpu-timers.c

@@ -180,14 +180,12 @@ posix_cpu_clock_set(const clockid_t clock, const struct timespec64 *tp)
 }
 
 /*
- * Sample a per-thread clock for the given task.
+ * Sample a per-thread clock for the given task. clkid is validated.
  */
-static int cpu_clock_sample(const clockid_t which_clock,
-			    struct task_struct *p, u64 *sample)
+static void cpu_clock_sample(const clockid_t clkid, struct task_struct *p,
+			     u64 *sample)
 {
-	switch (CPUCLOCK_WHICH(which_clock)) {
-	default:
-		return -EINVAL;
+	switch (clkid) {
 	case CPUCLOCK_PROF:
 		*sample = prof_ticks(p);
 		break;
@@ -197,8 +195,9 @@ static int cpu_clock_sample(const clockid_t which_clock,
 	case CPUCLOCK_SCHED:
 		*sample = task_sched_runtime(p);
 		break;
+	default:
+		WARN_ON_ONCE(1);
 	}
-	return 0;
 }
 
 /*
@@ -297,10 +296,10 @@ thread_group_start_cputime(struct task_struct *tsk, struct task_cputime *times)
  * Sample a process (thread group) clock for the given task clkid. If the
  * group's cputime accounting is already enabled, read the atomic
  * store. Otherwise a full update is required.  Task's sighand lock must be
- * held to protect the task traversal on a full update.
+ * held to protect the task traversal on a full update. clkid is already
+ * validated.
  */
-static int cpu_clock_sample_group(const clockid_t which_clock,
-				  struct task_struct *p,
+static void cpu_clock_sample_group(const clockid_t clkid, struct task_struct *p,
 				   u64 *sample, bool start)
 {
 	struct thread_group_cputimer *cputimer = &p->signal->cputimer;
@@ -315,9 +314,7 @@ static int cpu_clock_sample_group(const clockid_t which_clock,
 		sample_cputime_atomic(&cputime, &cputimer->cputime_atomic);
 	}
 
-	switch (CPUCLOCK_WHICH(which_clock)) {
-	default:
-		return -EINVAL;
+	switch (clkid) {
 	case CPUCLOCK_PROF:
 		*sample = cputime.utime + cputime.stime;
 		break;
@@ -327,8 +324,9 @@ static int cpu_clock_sample_group(const clockid_t which_clock,
 	case CPUCLOCK_SCHED:
 		*sample = cputime.sum_exec_runtime;
 		break;
+	default:
+		WARN_ON_ONCE(1);
 	}
-	return 0;
 }
 
 static int posix_cpu_clock_get(const clockid_t clock, struct timespec64 *tp)