time: Rename tsk->real_start_time to ->start_boottime

Since it stores CLOCK_BOOTTIME, not, as the name suggests,
CLOCK_REALTIME, let's rename ->real_start_time to ->start_bootime.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>

Author: Peter Zijlstra

fs/exec.c

@@ -1132,7 +1132,7 @@ static int de_thread(struct task_struct *tsk)
 		 * also take its birthdate (always earlier than our own).
 		 */
 		tsk->start_time = leader->start_time;
-		tsk->real_start_time = leader->real_start_time;
+		tsk->start_boottime = leader->start_boottime;
 
 		BUG_ON(!same_thread_group(leader, tsk));
 		BUG_ON(has_group_leader_pid(tsk));

fs/proc/array.c

@@ -533,7 +533,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
 	nice = task_nice(task);
 
 	/* convert nsec -> ticks */
-	start_time = nsec_to_clock_t(task->real_start_time);
+	start_time = nsec_to_clock_t(task->start_boottime);
 
 	seq_put_decimal_ull(m, "", pid_nr_ns(pid, ns));
 	seq_puts(m, " (");

include/linux/sched.h

@@ -857,7 +857,7 @@ struct task_struct {
 	u64				start_time;
 
 	/* Boot based time in nsecs: */
-	u64				real_start_time;
+	u64				start_boottime;
 
 	/* MM fault and swap info: this can arguably be seen as either mm-specific or thread-specific: */
 	unsigned long			min_flt;

kernel/fork.c

@@ -2130,7 +2130,7 @@ static __latent_entropy struct task_struct *copy_process(
 	 */
 
 	p->start_time = ktime_get_ns();
-	p->real_start_time = ktime_get_boottime_ns();
+	p->start_boottime = ktime_get_boottime_ns();
 
 	/*
 	 * Make it visible to the rest of the system, but dont wake it up yet.