cgroup: kill cgrp_ss_priv[CGROUP_CANFORK_COUNT] and friends

Now that nobody use the "priv" arg passed to can_fork/cancel_fork/fork we can
kill CGROUP_CANFORK_COUNT/SUBSYS_TAG/etc and cgrp_ss_priv[] in copy_process().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

3 files changed, 9 insertions, 40 deletions

diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index 678cd5e4e881..8cfbc9dfd650 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -34,17 +34,12 @@ struct seq_file;
 
 /* define the enumeration of all cgroup subsystems */
 #define SUBSYS(_x) _x ## _cgrp_id,
-#define SUBSYS_TAG(_t) CGROUP_ ## _t, \
-	__unused_tag_ ## _t = CGROUP_ ## _t - 1,
 enum cgroup_subsys_id {
 #include <linux/cgroup_subsys.h>
 	CGROUP_SUBSYS_COUNT,
 };
-#undef SUBSYS_TAG
 #undef SUBSYS
 
-#define CGROUP_CANFORK_COUNT (CGROUP_CANFORK_END - CGROUP_CANFORK_START)
-
 /* bits in struct cgroup_subsys_state flags field */
 enum {
 	CSS_NO_REF	= (1 << 0), /* no reference counting for this css */
@@ -424,9 +419,9 @@ struct cgroup_subsys {
 	int (*can_attach)(struct cgroup_taskset *tset);
 	void (*cancel_attach)(struct cgroup_taskset *tset);
 	void (*attach)(struct cgroup_taskset *tset);
-	int (*can_fork)(struct task_struct *task, void **priv_p);
-	void (*cancel_fork)(struct task_struct *task, void *priv);
-	void (*fork)(struct task_struct *task, void *priv);
+	int (*can_fork)(struct task_struct *task);
+	void (*cancel_fork)(struct task_struct *task);
+	void (*fork)(struct task_struct *task);
 	void (*exit)(struct task_struct *task);
 	void (*free)(struct task_struct *task);
 	void (*bind)(struct cgroup_subsys_state *root_css);
@@ -512,7 +507,6 @@ static inline void cgroup_threadgroup_change_end(struct task_struct *tsk)
 
 #else	/* CONFIG_CGROUPS */
 
-#define CGROUP_CANFORK_COUNT 0
 #define CGROUP_SUBSYS_COUNT 0
 
 static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) {}
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index cb91b44f5f78..2b3e231448ca 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -96,12 +96,9 @@ int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
 		     struct pid *pid, struct task_struct *tsk);
 
 void cgroup_fork(struct task_struct *p);
-extern int cgroup_can_fork(struct task_struct *p,
-			   void *ss_priv[CGROUP_CANFORK_COUNT]);
-extern void cgroup_cancel_fork(struct task_struct *p,
-			       void *ss_priv[CGROUP_CANFORK_COUNT]);
-extern void cgroup_post_fork(struct task_struct *p,
-			     void *old_ss_priv[CGROUP_CANFORK_COUNT]);
+extern int cgroup_can_fork(struct task_struct *p);
+extern void cgroup_cancel_fork(struct task_struct *p);
+extern void cgroup_post_fork(struct task_struct *p);
 void cgroup_exit(struct task_struct *p);
 void cgroup_free(struct task_struct *p);
 
@@ -539,13 +536,9 @@ static inline int cgroupstats_build(struct cgroupstats *stats,
 				    struct dentry *dentry) { return -EINVAL; }
 
 static inline void cgroup_fork(struct task_struct *p) {}
-static inline int cgroup_can_fork(struct task_struct *p,
-				  void *ss_priv[CGROUP_CANFORK_COUNT])
-{ return 0; }
-static inline void cgroup_cancel_fork(struct task_struct *p,
-				      void *ss_priv[CGROUP_CANFORK_COUNT]) {}
-static inline void cgroup_post_fork(struct task_struct *p,
-				    void *ss_priv[CGROUP_CANFORK_COUNT]) {}
+static inline int cgroup_can_fork(struct task_struct *p) { return 0; }
+static inline void cgroup_cancel_fork(struct task_struct *p) {}
+static inline void cgroup_post_fork(struct task_struct *p) {}
 static inline void cgroup_exit(struct task_struct *p) {}
 static inline void cgroup_free(struct task_struct *p) {}
 
diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h
index 1a96fdaa33d5..0df0336acee9 100644
--- a/include/linux/cgroup_subsys.h
+++ b/include/linux/cgroup_subsys.h
@@ -6,14 +6,8 @@
 
 /*
  * This file *must* be included with SUBSYS() defined.
- * SUBSYS_TAG() is a noop if undefined.
  */
 
-#ifndef SUBSYS_TAG
-#define __TMP_SUBSYS_TAG
-#define SUBSYS_TAG(_x)
-#endif
-
 #if IS_ENABLED(CONFIG_CPUSETS)
 SUBSYS(cpuset)
 #endif
@@ -58,17 +52,10 @@ SUBSYS(net_prio)
 SUBSYS(hugetlb)
 #endif
 
-/*
- * Subsystems that implement the can_fork() family of callbacks.
- */
-SUBSYS_TAG(CANFORK_START)
-
 #if IS_ENABLED(CONFIG_CGROUP_PIDS)
 SUBSYS(pids)
 #endif
 
-SUBSYS_TAG(CANFORK_END)
-
 /*
  * The following subsystems are not supported on the default hierarchy.
  */
@@ -76,11 +63,6 @@ SUBSYS_TAG(CANFORK_END)
 SUBSYS(debug)
 #endif
 
-#ifdef __TMP_SUBSYS_TAG
-#undef __TMP_SUBSYS_TAG
-#undef SUBSYS_TAG
-#endif
-
 /*
  * DO NOT ADD ANY SUBSYSTEM WITHOUT EXPLICIT ACKS FROM CGROUP MAINTAINERS.
  */