uid_cputime: Extends the cputime functionality to report power per uid

/proc/uid_cputime/show_uid_stats shows a third field power for each of
the uids. It represents the power in the units (uAusec)

Bug: 21498425
Change-Id: I52fdc5e59647e9dc97561a26d56f462a2689ba9c
Signed-off-by: Ruchi Kandoi <kandoiruchi@google.com>

drivers/misc/uid_cputime.c

@@ -38,6 +38,8 @@ struct uid_entry {
 	cputime_t stime;
 	cputime_t active_utime;
 	cputime_t active_stime;
+	unsigned long long active_power;
+	unsigned long long power;
 	struct hlist_node hash;
 };
 
@@ -83,6 +85,7 @@ static int uid_stat_show(struct seq_file *m, void *v)
 	hash_for_each(hash_table, bkt, uid_entry, hash) {
 		uid_entry->active_stime = 0;
 		uid_entry->active_utime = 0;
+		uid_entry->active_power = 0;
 	}
 
 	read_lock(&tasklist_lock);
@@ -100,6 +103,7 @@ static int uid_stat_show(struct seq_file *m, void *v)
 		task_cputime_adjusted(task, &utime, &stime);
 		uid_entry->active_utime += utime;
 		uid_entry->active_stime += stime;
+		uid_entry->active_power += task->cpu_power;
 	}
 	read_unlock(&tasklist_lock);
 
@@ -108,9 +112,12 @@ static int uid_stat_show(struct seq_file *m, void *v)
 							uid_entry->active_utime;
 		cputime_t total_stime = uid_entry->stime +
 							uid_entry->active_stime;
-		seq_printf(m, "%d: %u %u\n", uid_entry->uid,
+		unsigned long long total_power = uid_entry->power +
+							uid_entry->active_power;
+		seq_printf(m, "%d: %u %u %llu\n", uid_entry->uid,
 						cputime_to_usecs(total_utime),
-						cputime_to_usecs(total_stime));
+						cputime_to_usecs(total_stime),
+						total_power);
 	}
 
 	mutex_unlock(&uid_lock);
@@ -203,6 +210,7 @@ static int process_notifier(struct notifier_block *self,
 	task_cputime_adjusted(task, &utime, &stime);
 	uid_entry->utime += utime;
 	uid_entry->stime += stime;
+	uid_entry->power += task->cpu_power;
 
 exit:
 	mutex_unlock(&uid_lock);