cgroup: convert all non-memcg controllers to the new cftype interface

Convert debug, freezer, cpuset, cpu_cgroup, cpuacct, net_prio, blkio,
net_cls and device controllers to use the new cftype based interface.
Termination entry is added to cftype arrays and populate callbacks are
replaced with cgroup_subsys->base_cftypes initializations.

This is functionally identical transformation.  There shouldn't be any
visible behavior change.

memcg is rather special and will be converted separately.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <paul@paulmenage.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Vivek Goyal <vgoyal@redhat.com>

block/blk-cgroup.c

@@ -1515,14 +1515,9 @@ struct cftype blkio_files[] = {
 		.read_map = blkiocg_file_read_map,
 	},
 #endif
+	{ }	/* terminate */
 };
 
-static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
-{
-	return cgroup_add_files(cgroup, subsys, blkio_files,
-				ARRAY_SIZE(blkio_files));
-}
-
 static void blkiocg_destroy(struct cgroup *cgroup)
 {
 	struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
@@ -1642,11 +1637,11 @@ struct cgroup_subsys blkio_subsys = {
 	.can_attach = blkiocg_can_attach,
 	.attach = blkiocg_attach,
 	.destroy = blkiocg_destroy,
-	.populate = blkiocg_populate,
 #ifdef CONFIG_BLK_CGROUP
 	/* note: blkio_subsys_id is otherwise defined in blk-cgroup.h */
 	.subsys_id = blkio_subsys_id,
 #endif
+	.base_cftypes = blkio_files,
 	.use_id = 1,
 	.module = THIS_MODULE,
 };

kernel/cgroup.c

@@ -5349,19 +5349,15 @@ static struct cftype debug_files[] =  {
 		.name = "releasable",
 		.read_u64 = releasable_read,
 	},
-};
 
-static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont)
-{
-	return cgroup_add_files(cont, ss, debug_files,
-				ARRAY_SIZE(debug_files));
-}
+	{ }	/* terminate */
+};
 
 struct cgroup_subsys debug_subsys = {
 	.name = "debug",
 	.create = debug_create,
 	.destroy = debug_destroy,
-	.populate = debug_populate,
 	.subsys_id = debug_subsys_id,
+	.base_cftypes = debug_files,
 };
 #endif /* CONFIG_CGROUP_DEBUG */

kernel/cgroup_freezer.c

@@ -358,24 +358,19 @@ static int freezer_write(struct cgroup *cgroup,
 static struct cftype files[] = {
 	{
 		.name = "state",
+		.flags = CFTYPE_NOT_ON_ROOT,
 		.read_seq_string = freezer_read,
 		.write_string = freezer_write,
 	},
+	{ }	/* terminate */
 };
 
-static int freezer_populate(struct cgroup_subsys *ss, struct cgroup *cgroup)
-{
-	if (!cgroup->parent)
-		return 0;
-	return cgroup_add_files(cgroup, ss, files, ARRAY_SIZE(files));
-}
-
 struct cgroup_subsys freezer_subsys = {
 	.name		= "freezer",
 	.create		= freezer_create,
 	.destroy	= freezer_destroy,
-	.populate	= freezer_populate,
 	.subsys_id	= freezer_subsys_id,
 	.can_attach	= freezer_can_attach,
 	.fork		= freezer_fork,
+	.base_cftypes	= files,
 };

kernel/cpuset.c

@@ -1765,28 +1765,17 @@ static struct cftype files[] = {
 		.write_u64 = cpuset_write_u64,
 		.private = FILE_SPREAD_SLAB,
 	},
-};
 
-static struct cftype cft_memory_pressure_enabled = {
+	{
 		.name = "memory_pressure_enabled",
+		.flags = CFTYPE_ONLY_ON_ROOT,
 		.read_u64 = cpuset_read_u64,
 		.write_u64 = cpuset_write_u64,
 		.private = FILE_MEMORY_PRESSURE_ENABLED,
-};
-
-static int cpuset_populate(struct cgroup_subsys *ss, struct cgroup *cont)
-{
-	int err;
+	},
 
-	err = cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
-	if (err)
-		return err;
-	/* memory_pressure_enabled is in root cpuset only */
-	if (!cont->parent)
-		err = cgroup_add_file(cont, ss,
-				      &cft_memory_pressure_enabled);
-	return err;
-}
+	{ }	/* terminate */
+};
 
 /*
  * post_clone() is called during cgroup_create() when the
@@ -1887,9 +1876,9 @@ struct cgroup_subsys cpuset_subsys = {
 	.destroy = cpuset_destroy,
 	.can_attach = cpuset_can_attach,
 	.attach = cpuset_attach,
-	.populate = cpuset_populate,
 	.post_clone = cpuset_post_clone,
 	.subsys_id = cpuset_subsys_id,
+	.base_cftypes = files,
 	.early_init = 1,
 };
 

kernel/sched/core.c

@@ -7970,13 +7970,9 @@ static struct cftype cpu_files[] = {
 		.write_u64 = cpu_rt_period_write_uint,
 	},
 #endif
+	{ }	/* terminate */
 };
 
-static int cpu_cgroup_populate(struct cgroup_subsys *ss, struct cgroup *cont)
-{
-	return cgroup_add_files(cont, ss, cpu_files, ARRAY_SIZE(cpu_files));
-}
-
 struct cgroup_subsys cpu_cgroup_subsys = {
 	.name		= "cpu",
 	.create		= cpu_cgroup_create,
@@ -7984,8 +7980,8 @@ struct cgroup_subsys cpu_cgroup_subsys = {
 	.can_attach	= cpu_cgroup_can_attach,
 	.attach		= cpu_cgroup_attach,
 	.exit		= cpu_cgroup_exit,
-	.populate	= cpu_cgroup_populate,
 	.subsys_id	= cpu_cgroup_subsys_id,
+	.base_cftypes	= cpu_files,
 	.early_init	= 1,
 };
 
@@ -8170,13 +8166,9 @@ static struct cftype files[] = {
 		.name = "stat",
 		.read_map = cpuacct_stats_show,
 	},
+	{ }	/* terminate */
 };
 
-static int cpuacct_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
-{
-	return cgroup_add_files(cgrp, ss, files, ARRAY_SIZE(files));
-}
-
 /*
  * charge this task's execution time to its accounting group.
  *
@@ -8208,7 +8200,7 @@ struct cgroup_subsys cpuacct_subsys = {
 	.name = "cpuacct",
 	.create = cpuacct_create,
 	.destroy = cpuacct_destroy,
-	.populate = cpuacct_populate,
 	.subsys_id = cpuacct_subsys_id,
+	.base_cftypes = files,
 };
 #endif	/* CONFIG_CGROUP_CPUACCT */

net/core/netprio_cgroup.c

@@ -242,21 +242,17 @@ static struct cftype ss_files[] = {
 		.read_map = read_priomap,
 		.write_string = write_priomap,
 	},
+	{ }	/* terminate */
 };
 
-static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
-{
-	return cgroup_add_files(cgrp, ss, ss_files, ARRAY_SIZE(ss_files));
-}
-
 struct cgroup_subsys net_prio_subsys = {
 	.name		= "net_prio",
 	.create		= cgrp_create,
 	.destroy	= cgrp_destroy,
-	.populate	= cgrp_populate,
 #ifdef CONFIG_NETPRIO_CGROUP
 	.subsys_id	= net_prio_subsys_id,
 #endif
+	.base_cftypes	= ss_files,
 	.module		= THIS_MODULE
 };
 

net/sched/cls_cgroup.c

@@ -70,21 +70,17 @@ static struct cftype ss_files[] = {
 		.read_u64 = read_classid,
 		.write_u64 = write_classid,
 	},
+	{ }	/* terminate */
 };
 
-static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
-{
-	return cgroup_add_files(cgrp, ss, ss_files, ARRAY_SIZE(ss_files));
-}
-
 struct cgroup_subsys net_cls_subsys = {
 	.name		= "net_cls",
 	.create		= cgrp_create,
 	.destroy	= cgrp_destroy,
-	.populate	= cgrp_populate,
 #ifdef CONFIG_NET_CLS_CGROUP
 	.subsys_id	= net_cls_subsys_id,
 #endif
+	.base_cftypes	= ss_files,
 	.module		= THIS_MODULE,
 };
 

security/device_cgroup.c

@@ -447,22 +447,16 @@ static struct cftype dev_cgroup_files[] = {
 		.read_seq_string = devcgroup_seq_read,
 		.private = DEVCG_LIST,
 	},
+	{ }	/* terminate */
 };
 
-static int devcgroup_populate(struct cgroup_subsys *ss,
-				struct cgroup *cgroup)
-{
-	return cgroup_add_files(cgroup, ss, dev_cgroup_files,
-					ARRAY_SIZE(dev_cgroup_files));
-}
-
 struct cgroup_subsys devices_subsys = {
 	.name = "devices",
 	.can_attach = devcgroup_can_attach,
 	.create = devcgroup_create,
 	.destroy = devcgroup_destroy,
-	.populate = devcgroup_populate,
 	.subsys_id = devices_subsys_id,
+	.base_cftypes = dev_cgroup_files,
 };
 
 int __devcgroup_inode_permission(struct inode *inode, int mask)