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>

diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index 678cd5e..8cfbc9d 100644 (file)
--- 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 cb91b44..2b3e231 100644 (file)
--- 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 1a96fda..0df0336 100644 (file)
--- 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.
  */

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index ad35ac0..7f2f007 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5488,19 +5488,6 @@ static const struct file_operations proc_cgroupstats_operations = {
        .release = single_release,
 };
 
-static void **subsys_canfork_priv_p(void *ss_priv[CGROUP_CANFORK_COUNT], int i)
-{
-       if (CGROUP_CANFORK_START <= i && i < CGROUP_CANFORK_END)
-               return &ss_priv[i - CGROUP_CANFORK_START];
-       return NULL;
-}
-
-static void *subsys_canfork_priv(void *ss_priv[CGROUP_CANFORK_COUNT], int i)
-{
-       void **private = subsys_canfork_priv_p(ss_priv, i);
-       return private ? *private : NULL;
-}
-
 /**
  * cgroup_fork - initialize cgroup related fields during copy_process()
  * @child: pointer to task_struct of forking parent process.
@@ -5523,14 +5510,13 @@ void cgroup_fork(struct task_struct *child)
  * returns an error, the fork aborts with that error code. This allows for
  * a cgroup subsystem to conditionally allow or deny new forks.
  */
-int cgroup_can_fork(struct task_struct *child,
-                   void *ss_priv[CGROUP_CANFORK_COUNT])
+int cgroup_can_fork(struct task_struct *child)
 {
        struct cgroup_subsys *ss;
        int i, j, ret;
 
        for_each_subsys_which(ss, i, &have_canfork_callback) {
-               ret = ss->can_fork(child, subsys_canfork_priv_p(ss_priv, i));
+               ret = ss->can_fork(child);
                if (ret)
                        goto out_revert;
        }
@@ -5542,7 +5528,7 @@ out_revert:
                if (j >= i)
                        break;
                if (ss->cancel_fork)
-                       ss->cancel_fork(child, subsys_canfork_priv(ss_priv, j));
+                       ss->cancel_fork(child);
        }
 
        return ret;
@@ -5555,15 +5541,14 @@ out_revert:
  * This calls the cancel_fork() callbacks if a fork failed *after*
  * cgroup_can_fork() succeded.
  */
-void cgroup_cancel_fork(struct task_struct *child,
-                       void *ss_priv[CGROUP_CANFORK_COUNT])
+void cgroup_cancel_fork(struct task_struct *child)
 {
        struct cgroup_subsys *ss;
        int i;
 
        for_each_subsys(ss, i)
                if (ss->cancel_fork)
-                       ss->cancel_fork(child, subsys_canfork_priv(ss_priv, i));
+                       ss->cancel_fork(child);
 }
 
 /**
@@ -5576,8 +5561,7 @@ void cgroup_cancel_fork(struct task_struct *child,
  * cgroup_task_iter_start() - to guarantee that the new task ends up on its
  * list.
  */
-void cgroup_post_fork(struct task_struct *child,
-                     void *old_ss_priv[CGROUP_CANFORK_COUNT])
+void cgroup_post_fork(struct task_struct *child)
 {
        struct cgroup_subsys *ss;
        int i;
@@ -5621,7 +5605,7 @@ void cgroup_post_fork(struct task_struct *child,
         * and addition to css_set.
         */
        for_each_subsys_which(ss, i, &have_fork_callback)
-               ss->fork(child, subsys_canfork_priv(old_ss_priv, i));
+               ss->fork(child);
 }
 
 /**

diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 2d3df82..1b72d56 100644 (file)
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -200,7 +200,7 @@ static void freezer_attach(struct cgroup_taskset *tset)
  * to do anything as freezer_attach() will put @task into the appropriate
  * state.
  */
-static void freezer_fork(struct task_struct *task, void *private)
+static void freezer_fork(struct task_struct *task)
 {
        struct freezer *freezer;
 

diff --git a/kernel/cgroup_pids.c b/kernel/cgroup_pids.c
index b50d5a1..18107ae 100644 (file)
--- a/kernel/cgroup_pids.c
+++ b/kernel/cgroup_pids.c
@@ -209,7 +209,7 @@ static void pids_cancel_attach(struct cgroup_taskset *tset)
  * task_css_check(true) in pids_can_fork() and pids_cancel_fork() relies
  * on threadgroup_change_begin() held by the copy_process().
  */
-static int pids_can_fork(struct task_struct *task, void **priv_p)
+static int pids_can_fork(struct task_struct *task)
 {
        struct cgroup_subsys_state *css;
        struct pids_cgroup *pids;
@@ -219,7 +219,7 @@ static int pids_can_fork(struct task_struct *task, void **priv_p)
        return pids_try_charge(pids, 1);
 }
 
-static void pids_cancel_fork(struct task_struct *task, void *priv)
+static void pids_cancel_fork(struct task_struct *task)
 {
        struct cgroup_subsys_state *css;
        struct pids_cgroup *pids;

diff --git a/kernel/fork.c b/kernel/fork.c
index fce002e..ba7d1c0 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1249,7 +1249,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 {
        int retval;
        struct task_struct *p;
-       void *cgrp_ss_priv[CGROUP_CANFORK_COUNT] = {};
 
        if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
                return ERR_PTR(-EINVAL);
@@ -1526,7 +1525,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         * between here and cgroup_post_fork() if an organisation operation is in
         * progress.
         */
-       retval = cgroup_can_fork(p, cgrp_ss_priv);
+       retval = cgroup_can_fork(p);
        if (retval)
                goto bad_fork_free_pid;
 
@@ -1608,7 +1607,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
        write_unlock_irq(&tasklist_lock);
 
        proc_fork_connector(p);
-       cgroup_post_fork(p, cgrp_ss_priv);
+       cgroup_post_fork(p);
        threadgroup_change_end(current);
        perf_event_fork(p);
 
@@ -1618,7 +1617,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
        return p;
 
 bad_fork_cancel_cgroup:
-       cgroup_cancel_fork(p, cgrp_ss_priv);
+       cgroup_cancel_fork(p);
 bad_fork_free_pid:
        if (pid != &init_struct_pid)
                free_pid(pid);

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a9db481..b7d2271 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8212,7 +8212,7 @@ static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css)
        sched_offline_group(tg);
 }
 
-static void cpu_cgroup_fork(struct task_struct *task, void *private)
+static void cpu_cgroup_fork(struct task_struct *task)
 {
        sched_move_task(task);
 }