Merge branch 'for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/g…

…it/tj/cgroup

Pull cgroup changes from Tejun Heo:
 "Out of the 8 commits, one fixes a long-standing locking issue around
  tasklist walking and others are cleanups."

* 'for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: Walk task list under tasklist_lock in cgroup_enable_task_cg_list
  cgroup: Remove wrong comment on cgroup_enable_task_cg_list()
  cgroup: remove cgroup_subsys argument from callbacks
  cgroup: remove extra calls to find_existing_css_set
  cgroup: replace tasklist_lock with rcu_read_lock
  cgroup: simplify double-check locking in cgroup_attach_proc
  cgroup: move struct cgroup_pidlist out from the header file
  cgroup: remove cgroup_attach_task_current_cg()

Documentation/cgroups/cgroups.txt

@@ -558,8 +558,7 @@ Each subsystem may export the following methods. The only mandatory
 methods are create/destroy. Any others that are null are presumed to
 be successful no-ops.
 
-struct cgroup_subsys_state *create(struct cgroup_subsys *ss,
-				   struct cgroup *cgrp)
+struct cgroup_subsys_state *create(struct cgroup *cgrp)
 (cgroup_mutex held by caller)
 
 Called to create a subsystem state object for a cgroup. The
@@ -574,7 +573,7 @@ identified by the passed cgroup object having a NULL parent (since
 it's the root of the hierarchy) and may be an appropriate place for
 initialization code.
 
-void destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
+void destroy(struct cgroup *cgrp)
 (cgroup_mutex held by caller)
 
 The cgroup system is about to destroy the passed cgroup; the subsystem
@@ -585,16 +584,15 @@ cgroup->parent is still valid. (Note - can also be called for a
 newly-created cgroup if an error occurs after this subsystem's
 create() method has been called for the new cgroup).
 
-int pre_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp);
+int pre_destroy(struct cgroup *cgrp);
 
 Called before checking the reference count on each subsystem. This may
 be useful for subsystems which have some extra references even if
 there are not tasks in the cgroup. If pre_destroy() returns error code,
 rmdir() will fail with it. From this behavior, pre_destroy() can be
 called multiple times against a cgroup.
 
-int can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
-	       struct cgroup_taskset *tset)
+int can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 (cgroup_mutex held by caller)
 
 Called prior to moving one or more tasks into a cgroup; if the
@@ -615,8 +613,7 @@ fork. If this method returns 0 (success) then this should remain valid
 while the caller holds cgroup_mutex and it is ensured that either
 attach() or cancel_attach() will be called in future.
 
-void cancel_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
-		   struct cgroup_taskset *tset)
+void cancel_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 (cgroup_mutex held by caller)
 
 Called when a task attach operation has failed after can_attach() has succeeded.
@@ -625,23 +622,22 @@ function, so that the subsystem can implement a rollback. If not, not necessary.
 This will be called only about subsystems whose can_attach() operation have
 succeeded. The parameters are identical to can_attach().
 
-void attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
-	    struct cgroup_taskset *tset)
+void attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 (cgroup_mutex held by caller)
 
 Called after the task has been attached to the cgroup, to allow any
 post-attachment activity that requires memory allocations or blocking.
 The parameters are identical to can_attach().
 
-void fork(struct cgroup_subsy *ss, struct task_struct *task)
+void fork(struct task_struct *task)
 
 Called when a task is forked into a cgroup.
 
-void exit(struct cgroup_subsys *ss, struct task_struct *task)
+void exit(struct task_struct *task)
 
 Called during task exit.
 
-int populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
+int populate(struct cgroup *cgrp)
 (cgroup_mutex held by caller)
 
 Called after creation of a cgroup to allow a subsystem to populate
@@ -651,15 +647,15 @@ include/linux/cgroup.h for details).  Note that although this
 method can return an error code, the error code is currently not
 always handled well.
 
-void post_clone(struct cgroup_subsys *ss, struct cgroup *cgrp)
+void post_clone(struct cgroup *cgrp)
 (cgroup_mutex held by caller)
 
 Called during cgroup_create() to do any parameter
 initialization which might be required before a task could attach.  For
 example in cpusets, no task may attach before 'cpus' and 'mems' are set
 up.
 
-void bind(struct cgroup_subsys *ss, struct cgroup *root)
+void bind(struct cgroup *root)
 (cgroup_mutex and ss->hierarchy_mutex held by caller)
 
 Called when a cgroup subsystem is rebound to a different hierarchy

block/blk-cgroup.c

@@ -28,13 +28,10 @@ static LIST_HEAD(blkio_list);
 struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
 EXPORT_SYMBOL_GPL(blkio_root_cgroup);
 
-static struct cgroup_subsys_state *blkiocg_create(struct cgroup_subsys *,
-						  struct cgroup *);
-static int blkiocg_can_attach(struct cgroup_subsys *, struct cgroup *,
-			      struct cgroup_taskset *);
-static void blkiocg_attach(struct cgroup_subsys *, struct cgroup *,
-			   struct cgroup_taskset *);
-static void blkiocg_destroy(struct cgroup_subsys *, struct cgroup *);
+static struct cgroup_subsys_state *blkiocg_create(struct cgroup *);
+static int blkiocg_can_attach(struct cgroup *, struct cgroup_taskset *);
+static void blkiocg_attach(struct cgroup *, struct cgroup_taskset *);
+static void blkiocg_destroy(struct cgroup *);
 static int blkiocg_populate(struct cgroup_subsys *, struct cgroup *);
 
 /* for encoding cft->private value on file */
@@ -1548,7 +1545,7 @@ static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
 				ARRAY_SIZE(blkio_files));
 }
 
-static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
+static void blkiocg_destroy(struct cgroup *cgroup)
 {
 	struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
 	unsigned long flags;
@@ -1598,8 +1595,7 @@ static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
 		kfree(blkcg);
 }
 
-static struct cgroup_subsys_state *
-blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
+static struct cgroup_subsys_state *blkiocg_create(struct cgroup *cgroup)
 {
 	struct blkio_cgroup *blkcg;
 	struct cgroup *parent = cgroup->parent;
@@ -1628,8 +1624,7 @@ blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
  * of the main cic data structures.  For now we allow a task to change
  * its cgroup only if it's the only owner of its ioc.
  */
-static int blkiocg_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
-			      struct cgroup_taskset *tset)
+static int blkiocg_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 {
 	struct task_struct *task;
 	struct io_context *ioc;
@@ -1648,8 +1643,7 @@ static int blkiocg_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
 	return ret;
 }
 
-static void blkiocg_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
-			   struct cgroup_taskset *tset)
+static void blkiocg_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 {
 	struct task_struct *task;
 	struct io_context *ioc;

include/linux/cgroup.h

@@ -160,38 +160,6 @@ enum {
 	CGRP_CLONE_CHILDREN,
 };
 
-/* which pidlist file are we talking about? */
-enum cgroup_filetype {
-	CGROUP_FILE_PROCS,
-	CGROUP_FILE_TASKS,
-};
-
-/*
- * A pidlist is a list of pids that virtually represents the contents of one
- * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
- * a pair (one each for procs, tasks) for each pid namespace that's relevant
- * to the cgroup.
- */
-struct cgroup_pidlist {
-	/*
-	 * used to find which pidlist is wanted. doesn't change as long as
-	 * this particular list stays in the list.
-	 */
-	struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
-	/* array of xids */
-	pid_t *list;
-	/* how many elements the above list has */
-	int length;
-	/* how many files are using the current array */
-	int use_count;
-	/* each of these stored in a list by its cgroup */
-	struct list_head links;
-	/* pointer to the cgroup we belong to, for list removal purposes */
-	struct cgroup *owner;
-	/* protects the other fields */
-	struct rw_semaphore mutex;
-};
-
 struct cgroup {
 	unsigned long flags;		/* "unsigned long" so bitops work */
 
@@ -484,23 +452,18 @@ int cgroup_taskset_size(struct cgroup_taskset *tset);
  */
 
 struct cgroup_subsys {
-	struct cgroup_subsys_state *(*create)(struct cgroup_subsys *ss,
-						  struct cgroup *cgrp);
-	int (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
-	void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
-	int (*can_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
-			  struct cgroup_taskset *tset);
-	void (*cancel_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
-			      struct cgroup_taskset *tset);
-	void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
-		       struct cgroup_taskset *tset);
-	void (*fork)(struct cgroup_subsys *ss, struct task_struct *task);
-	void (*exit)(struct cgroup_subsys *ss, struct cgroup *cgrp,
-			struct cgroup *old_cgrp, struct task_struct *task);
-	int (*populate)(struct cgroup_subsys *ss,
-			struct cgroup *cgrp);
-	void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp);
-	void (*bind)(struct cgroup_subsys *ss, struct cgroup *root);
+	struct cgroup_subsys_state *(*create)(struct cgroup *cgrp);
+	int (*pre_destroy)(struct cgroup *cgrp);
+	void (*destroy)(struct cgroup *cgrp);
+	int (*can_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
+	void (*cancel_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
+	void (*attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
+	void (*fork)(struct task_struct *task);
+	void (*exit)(struct cgroup *cgrp, struct cgroup *old_cgrp,
+		     struct task_struct *task);
+	int (*populate)(struct cgroup_subsys *ss, struct cgroup *cgrp);
+	void (*post_clone)(struct cgroup *cgrp);
+	void (*bind)(struct cgroup *root);
 
 	int subsys_id;
 	int active;
@@ -602,11 +565,6 @@ int cgroup_scan_tasks(struct cgroup_scanner *scan);
 int cgroup_attach_task(struct cgroup *, struct task_struct *);
 int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
 
-static inline int cgroup_attach_task_current_cg(struct task_struct *tsk)
-{
-	return cgroup_attach_task_all(current, tsk);
-}
-
 /*
  * CSS ID is ID for cgroup_subsys_state structs under subsys. This only works
  * if cgroup_subsys.use_id == true. It can be used for looking up and scanning.
@@ -669,10 +627,6 @@ static inline int cgroup_attach_task_all(struct task_struct *from,
 {
 	return 0;
 }
-static inline int cgroup_attach_task_current_cg(struct task_struct *t)
-{
-	return 0;
-}
 
 #endif /* !CONFIG_CGROUPS */
 

include/net/sock.h

@@ -69,15 +69,15 @@ struct cgroup;
 struct cgroup_subsys;
 #ifdef CONFIG_NET
 int mem_cgroup_sockets_init(struct cgroup *cgrp, struct cgroup_subsys *ss);
-void mem_cgroup_sockets_destroy(struct cgroup *cgrp, struct cgroup_subsys *ss);
+void mem_cgroup_sockets_destroy(struct cgroup *cgrp);
 #else
 static inline
 int mem_cgroup_sockets_init(struct cgroup *cgrp, struct cgroup_subsys *ss)
 {
 	return 0;
 }
 static inline
-void mem_cgroup_sockets_destroy(struct cgroup *cgrp, struct cgroup_subsys *ss)
+void mem_cgroup_sockets_destroy(struct cgroup *cgrp)
 {
 }
 #endif
@@ -871,8 +871,7 @@ struct proto {
 	 */
 	int			(*init_cgroup)(struct cgroup *cgrp,
 					       struct cgroup_subsys *ss);
-	void			(*destroy_cgroup)(struct cgroup *cgrp,
-						  struct cgroup_subsys *ss);
+	void			(*destroy_cgroup)(struct cgroup *cgrp);
 	struct cg_proto		*(*proto_cgroup)(struct mem_cgroup *memcg);
 #endif
 };

include/net/tcp_memcontrol.h

@@ -13,7 +13,7 @@ struct tcp_memcontrol {
 
 struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg);
 int tcp_init_cgroup(struct cgroup *cgrp, struct cgroup_subsys *ss);
-void tcp_destroy_cgroup(struct cgroup *cgrp, struct cgroup_subsys *ss);
+void tcp_destroy_cgroup(struct cgroup *cgrp);
 unsigned long long tcp_max_memory(const struct mem_cgroup *memcg);
 void tcp_prot_mem(struct mem_cgroup *memcg, long val, int idx);
 #endif /* _TCP_MEMCG_H */