cgroup, sched: convert away from cftype->read_map()

In preparation of conversion to kernfs, cgroup file handling is being
consolidated so that it can be easily mapped to the seq_file based
interface of kernfs.

cftype->read_map() doesn't add any value and being replaced with
->read_seq_string().  Update cpu_stats_show() and cpuacct_stats_show()
accordingly.

This patch doesn't make any visible behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>

kernel/sched/core.c

@@ -7257,14 +7257,14 @@ static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
 }
 
 static int cpu_stats_show(struct cgroup_subsys_state *css, struct cftype *cft,
-		struct cgroup_map_cb *cb)
+			  struct seq_file *sf)
 {
 	struct task_group *tg = css_tg(css);
 	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
 
-	cb->fill(cb, "nr_periods", cfs_b->nr_periods);
-	cb->fill(cb, "nr_throttled", cfs_b->nr_throttled);
-	cb->fill(cb, "throttled_time", cfs_b->throttled_time);
+	seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
+	seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
+	seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
 
 	return 0;
 }
@@ -7318,7 +7318,7 @@ static struct cftype cpu_files[] = {
 	},
 	{
 		.name = "stat",
-		.read_map = cpu_stats_show,
+		.read_seq_string = cpu_stats_show,
 	},
 #endif
 #ifdef CONFIG_RT_GROUP_SCHED

kernel/sched/cpuacct.c

@@ -184,7 +184,7 @@ static const char * const cpuacct_stat_desc[] = {
 };
 
 static int cpuacct_stats_show(struct cgroup_subsys_state *css,
-			      struct cftype *cft, struct cgroup_map_cb *cb)
+			      struct cftype *cft, struct seq_file *sf)
 {
 	struct cpuacct *ca = css_ca(css);
 	int cpu;
@@ -196,7 +196,7 @@ static int cpuacct_stats_show(struct cgroup_subsys_state *css,
 		val += kcpustat->cpustat[CPUTIME_NICE];
 	}
 	val = cputime64_to_clock_t(val);
-	cb->fill(cb, cpuacct_stat_desc[CPUACCT_STAT_USER], val);
+	seq_printf(sf, "%s %lld\n", cpuacct_stat_desc[CPUACCT_STAT_USER], val);
 
 	val = 0;
 	for_each_online_cpu(cpu) {
@@ -207,7 +207,7 @@ static int cpuacct_stats_show(struct cgroup_subsys_state *css,
 	}
 
 	val = cputime64_to_clock_t(val);
-	cb->fill(cb, cpuacct_stat_desc[CPUACCT_STAT_SYSTEM], val);
+	seq_printf(sf, "%s %lld\n", cpuacct_stat_desc[CPUACCT_STAT_SYSTEM], val);
 
 	return 0;
 }
@@ -224,7 +224,7 @@ static struct cftype files[] = {
 	},
 	{
 		.name = "stat",
-		.read_map = cpuacct_stats_show,
+		.read_seq_string = cpuacct_stats_show,
 	},
 	{ }	/* terminate */
 };