linux-kernel - [patch 20/44] posix-cpu-timers: Simplify sample functions

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Date:   Mon, 19 Aug 2019 16:32:01 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Oleg Nesterov <oleg@...hat.com>, Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        John Stultz <john.stultz@...aro.org>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Anna-Maria Behnsen <anna-maria@...utronix.de>
Subject: [patch 20/44] 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@...utronix.de>
---
 kernel/time/posix-cpu-timers.c |   28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -180,14 +180,12 @@ posix_cpu_clock_set(const clockid_t cloc
 }
 
 /*
- * 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 clocki
 	case CPUCLOCK_SCHED:
 		*sample = task_sched_runtime(p);
 		break;
+	default:
+		WARN_ON_ONCE(1);
 	}
-	return 0;
 }
 
 /*
@@ -297,11 +296,11 @@ thread_group_start_cputime(struct task_s
  * Sample a process (thread group) clock for the given task clkid. If the
  * groups cputime accounting is already enabled, read the atomic
  * store. Otherwise a full update is required.  task 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,
-				  u64 *sample, bool start)
+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;
 	struct task_cputime cputime;
@@ -315,9 +314,7 @@ static int cpu_clock_sample_group(const
 		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
 	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)