Merge branch 'for-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup updates from Tejun Heo:

 - xattr support added.  The implementation is shared with tmpfs.  The
   usage is restricted and intended to be used to manage per-cgroup
   metadata by system software.  tmpfs changes are routed through this
   branch with Hugh's permission.

 - cgroup subsystem ID handling simplified.

* 'for-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: Define CGROUP_SUBSYS_COUNT according the configuration
  cgroup: Assign subsystem IDs during compile time
  cgroup: Do not depend on a given order when populating the subsys array
  cgroup: Wrap subsystem selection macro
  cgroup: Remove CGROUP_BUILTIN_SUBSYS_COUNT
  cgroup: net_prio: Do not define task_netpioidx() when not selected
  cgroup: net_cls: Do not define task_cls_classid() when not selected
  cgroup: net_cls: Move sock_update_classid() declaration to cls_cgroup.h
  cgroup: trivial fixes for Documentation/cgroups/cgroups.txt
  xattr: mark variable as uninitialized to make both gcc and smatch happy
  fs: add missing documentation to simple_xattr functions
  cgroup: add documentation on extended attributes usage
  cgroup: rename subsys_bits to subsys_mask
  cgroup: add xattr support
  cgroup: revise how we re-populate root directory
  xattr: extract simple_xattr code from tmpfs

Documentation/cgroups/cgroups.txt

@@ -29,7 +29,8 @@ CONTENTS:
   3.1 Overview
   3.2 Synchronization
   3.3 Subsystem API
-4. Questions
+4. Extended attributes usage
+5. Questions
 
 1. Control Groups
 =================
@@ -62,9 +63,9 @@ an instance of the cgroup virtual filesystem associated with it.
 At any one time there may be multiple active hierarchies of task
 cgroups. Each hierarchy is a partition of all tasks in the system.
 
-User level code may create and destroy cgroups by name in an
+User-level code may create and destroy cgroups by name in an
 instance of the cgroup virtual file system, specify and query to
-which cgroup a task is assigned, and list the task pids assigned to
+which cgroup a task is assigned, and list the task PIDs assigned to
 a cgroup. Those creations and assignments only affect the hierarchy
 associated with that instance of the cgroup file system.
 
@@ -72,7 +73,7 @@ On their own, the only use for cgroups is for simple job
 tracking. The intention is that other subsystems hook into the generic
 cgroup support to provide new attributes for cgroups, such as
 accounting/limiting the resources which processes in a cgroup can
-access. For example, cpusets (see Documentation/cgroups/cpusets.txt) allows
+access. For example, cpusets (see Documentation/cgroups/cpusets.txt) allow
 you to associate a set of CPUs and a set of memory nodes with the
 tasks in each cgroup.
 
@@ -80,11 +81,11 @@ tasks in each cgroup.
 ----------------------------
 
 There are multiple efforts to provide process aggregations in the
-Linux kernel, mainly for resource tracking purposes. Such efforts
+Linux kernel, mainly for resource-tracking purposes. Such efforts
 include cpusets, CKRM/ResGroups, UserBeanCounters, and virtual server
 namespaces. These all require the basic notion of a
 grouping/partitioning of processes, with newly forked processes ending
-in the same group (cgroup) as their parent process.
+up in the same group (cgroup) as their parent process.
 
 The kernel cgroup patch provides the minimum essential kernel
 mechanisms required to efficiently implement such groups. It has
@@ -127,14 +128,14 @@ following lines:
                                / \
                Professors (15%)  students (5%)
 
-Browsers like Firefox/Lynx go into the WWW network class, while (k)nfsd go
-into NFS network class.
+Browsers like Firefox/Lynx go into the WWW network class, while (k)nfsd goes
+into the NFS network class.
 
 At the same time Firefox/Lynx will share an appropriate CPU/Memory class
 depending on who launched it (prof/student).
 
 With the ability to classify tasks differently for different resources
-(by putting those resource subsystems in different hierarchies) then
+(by putting those resource subsystems in different hierarchies),
 the admin can easily set up a script which receives exec notifications
 and depending on who is launching the browser he can
 
@@ -145,19 +146,19 @@ a separate cgroup for every browser launched and associate it with
 appropriate network and other resource class.  This may lead to
 proliferation of such cgroups.
 
-Also lets say that the administrator would like to give enhanced network
+Also let's say that the administrator would like to give enhanced network
 access temporarily to a student's browser (since it is night and the user
-wants to do online gaming :))  OR give one of the students simulation
-apps enhanced CPU power,
+wants to do online gaming :))  OR give one of the student's simulation
+apps enhanced CPU power.
 
-With ability to write pids directly to resource classes, it's just a
-matter of :
+With ability to write PIDs directly to resource classes, it's just a
+matter of:
 
        # echo pid > /sys/fs/cgroup/network/<new_class>/tasks
        (after some time)
        # echo pid > /sys/fs/cgroup/network/<orig_class>/tasks
 
-Without this ability, he would have to split the cgroup into
+Without this ability, the administrator would have to split the cgroup into
 multiple separate ones and then associate the new cgroups with the
 new resource classes.
 
@@ -184,20 +185,20 @@ Control Groups extends the kernel as follows:
    field of each task_struct using the css_set, anchored at
    css_set->tasks.
 
- - A cgroup hierarchy filesystem can be mounted  for browsing and
+ - A cgroup hierarchy filesystem can be mounted for browsing and
    manipulation from user space.
 
- - You can list all the tasks (by pid) attached to any cgroup.
+ - You can list all the tasks (by PID) attached to any cgroup.
 
 The implementation of cgroups requires a few, simple hooks
-into the rest of the kernel, none in performance critical paths:
+into the rest of the kernel, none in performance-critical paths:
 
  - in init/main.c, to initialize the root cgroups and initial
    css_set at system boot.
 
  - in fork and exit, to attach and detach a task from its css_set.
 
-In addition a new file system, of type "cgroup" may be mounted, to
+In addition, a new file system of type "cgroup" may be mounted, to
 enable browsing and modifying the cgroups presently known to the
 kernel.  When mounting a cgroup hierarchy, you may specify a
 comma-separated list of subsystems to mount as the filesystem mount
@@ -230,13 +231,13 @@ as the path relative to the root of the cgroup file system.
 Each cgroup is represented by a directory in the cgroup file system
 containing the following files describing that cgroup:
 
- - tasks: list of tasks (by pid) attached to that cgroup.  This list
-   is not guaranteed to be sorted.  Writing a thread id into this file
+ - tasks: list of tasks (by PID) attached to that cgroup.  This list
+   is not guaranteed to be sorted.  Writing a thread ID into this file
    moves the thread into this cgroup.
- - cgroup.procs: list of tgids in the cgroup.  This list is not
-   guaranteed to be sorted or free of duplicate tgids, and userspace
+ - cgroup.procs: list of thread group IDs in the cgroup.  This list is
+   not guaranteed to be sorted or free of duplicate TGIDs, and userspace
    should sort/uniquify the list if this property is required.
-   Writing a thread group id into this file moves all threads in that
+   Writing a thread group ID into this file moves all threads in that
    group into this cgroup.
  - notify_on_release flag: run the release agent on exit?
  - release_agent: the path to use for release notifications (this file
@@ -261,7 +262,7 @@ cgroup file system directories.
 
 When a task is moved from one cgroup to another, it gets a new
 css_set pointer - if there's an already existing css_set with the
-desired collection of cgroups then that group is reused, else a new
+desired collection of cgroups then that group is reused, otherwise a new
 css_set is allocated. The appropriate existing css_set is located by
 looking into a hash table.
 
@@ -292,7 +293,7 @@ file system) of the abandoned cgroup.  This enables automatic
 removal of abandoned cgroups.  The default value of
 notify_on_release in the root cgroup at system boot is disabled
 (0).  The default value of other cgroups at creation is the current
-value of their parents notify_on_release setting. The default value of
+value of their parents' notify_on_release settings. The default value of
 a cgroup hierarchy's release_agent path is empty.
 
 1.5 What does clone_children do ?
@@ -316,7 +317,7 @@ the "cpuset" cgroup subsystem, the steps are something like:
  4) Create the new cgroup by doing mkdir's and write's (or echo's) in
     the /sys/fs/cgroup virtual file system.
  5) Start a task that will be the "founding father" of the new job.
- 6) Attach that task to the new cgroup by writing its pid to the
+ 6) Attach that task to the new cgroup by writing its PID to the
     /sys/fs/cgroup/cpuset/tasks file for that cgroup.
  7) fork, exec or clone the job tasks from this founding father task.
 
@@ -344,7 +345,7 @@ and then start a subshell 'sh' in that cgroup:
 2.1 Basic Usage
 ---------------
 
-Creating, modifying, using the cgroups can be done through the cgroup
+Creating, modifying, using cgroups can be done through the cgroup
 virtual filesystem.
 
 To mount a cgroup hierarchy with all available subsystems, type:
@@ -441,7 +442,7 @@ You can attach the current shell task by echoing 0:
 # echo 0 > tasks
 
 You can use the cgroup.procs file instead of the tasks file to move all
-threads in a threadgroup at once. Echoing the pid of any task in a
+threads in a threadgroup at once. Echoing the PID of any task in a
 threadgroup to cgroup.procs causes all tasks in that threadgroup to be
 be attached to the cgroup. Writing 0 to cgroup.procs moves all tasks
 in the writing task's threadgroup.
@@ -479,7 +480,7 @@ in /proc/mounts and /proc/<pid>/cgroups.
 There is mechanism which allows to get notifications about changing
 status of a cgroup.
 
-To register new notification handler you need:
+To register a new notification handler you need to:
  - create a file descriptor for event notification using eventfd(2);
  - open a control file to be monitored (e.g. memory.usage_in_bytes);
  - write "<event_fd> <control_fd> <args>" to cgroup.event_control.
@@ -488,7 +489,7 @@ To register new notification handler you need:
 eventfd will be woken up by control file implementation or when the
 cgroup is removed.
 
-To unregister notification handler just close eventfd.
+To unregister a notification handler just close eventfd.
 
 NOTE: Support of notifications should be implemented for the control
 file. See documentation for the subsystem.
@@ -502,7 +503,7 @@ file. See documentation for the subsystem.
 Each kernel subsystem that wants to hook into the generic cgroup
 system needs to create a cgroup_subsys object. This contains
 various methods, which are callbacks from the cgroup system, along
-with a subsystem id which will be assigned by the cgroup system.
+with a subsystem ID which will be assigned by the cgroup system.
 
 Other fields in the cgroup_subsys object include:
 
@@ -516,7 +517,7 @@ Other fields in the cgroup_subsys object include:
   at system boot.
 
 Each cgroup object created by the system has an array of pointers,
-indexed by subsystem id; this pointer is entirely managed by the
+indexed by subsystem ID; this pointer is entirely managed by the
 subsystem; the generic cgroup code will never touch this pointer.
 
 3.2 Synchronization
@@ -639,7 +640,7 @@ void post_clone(struct cgroup *cgrp)
 
 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
+example, in cpusets, no task may attach before 'cpus' and 'mems' are set
 up.
 
 void bind(struct cgroup *root)
@@ -650,7 +651,26 @@ and root cgroup. Currently this will only involve movement between
 the default hierarchy (which never has sub-cgroups) and a hierarchy
 that is being created/destroyed (and hence has no sub-cgroups).
 
-4. Questions
+4. Extended attribute usage
+===========================
+
+cgroup filesystem supports certain types of extended attributes in its
+directories and files.  The current supported types are:
+	- Trusted (XATTR_TRUSTED)
+	- Security (XATTR_SECURITY)
+
+Both require CAP_SYS_ADMIN capability to set.
+
+Like in tmpfs, the extended attributes in cgroup filesystem are stored
+using kernel memory and it's advised to keep the usage at minimum.  This
+is the reason why user defined extended attributes are not supported, since
+any user can do it and there's no limit in the value size.
+
+The current known users for this feature are SELinux to limit cgroup usage
+in containers and systemd for assorted meta data like main PID in a cgroup
+(systemd creates a cgroup per service).
+
+5. Questions
 ============
 
 Q: what's up with this '/bin/echo' ?
@@ -660,5 +680,5 @@ A: bash's builtin 'echo' command does not check calls to write() against
 
 Q: When I attach processes, only the first of the line gets really attached !
 A: We can only return one error code per call to write(). So you should also
-   put only ONE pid.
+   put only ONE PID.
 

drivers/net/tun.c

@@ -68,6 +68,7 @@
 #include <net/netns/generic.h>
 #include <net/rtnetlink.h>
 #include <net/sock.h>
+#include <net/cls_cgroup.h>
 
 #include <asm/uaccess.h>
 

fs/xattr.c

@@ -791,3 +791,183 @@ EXPORT_SYMBOL(generic_getxattr);
 EXPORT_SYMBOL(generic_listxattr);
 EXPORT_SYMBOL(generic_setxattr);
 EXPORT_SYMBOL(generic_removexattr);
+
+/*
+ * Allocate new xattr and copy in the value; but leave the name to callers.
+ */
+struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)
+{
+	struct simple_xattr *new_xattr;
+	size_t len;
+
+	/* wrap around? */
+	len = sizeof(*new_xattr) + size;
+	if (len <= sizeof(*new_xattr))
+		return NULL;
+
+	new_xattr = kmalloc(len, GFP_KERNEL);
+	if (!new_xattr)
+		return NULL;
+
+	new_xattr->size = size;
+	memcpy(new_xattr->value, value, size);
+	return new_xattr;
+}
+
+/*
+ * xattr GET operation for in-memory/pseudo filesystems
+ */
+int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
+		     void *buffer, size_t size)
+{
+	struct simple_xattr *xattr;
+	int ret = -ENODATA;
+
+	spin_lock(&xattrs->lock);
+	list_for_each_entry(xattr, &xattrs->head, list) {
+		if (strcmp(name, xattr->name))
+			continue;
+
+		ret = xattr->size;
+		if (buffer) {
+			if (size < xattr->size)
+				ret = -ERANGE;
+			else
+				memcpy(buffer, xattr->value, xattr->size);
+		}
+		break;
+	}
+	spin_unlock(&xattrs->lock);
+	return ret;
+}
+
+static int __simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
+			      const void *value, size_t size, int flags)
+{
+	struct simple_xattr *xattr;
+	struct simple_xattr *uninitialized_var(new_xattr);
+	int err = 0;
+
+	/* value == NULL means remove */
+	if (value) {
+		new_xattr = simple_xattr_alloc(value, size);
+		if (!new_xattr)
+			return -ENOMEM;
+
+		new_xattr->name = kstrdup(name, GFP_KERNEL);
+		if (!new_xattr->name) {
+			kfree(new_xattr);
+			return -ENOMEM;
+		}
+	}
+
+	spin_lock(&xattrs->lock);
+	list_for_each_entry(xattr, &xattrs->head, list) {
+		if (!strcmp(name, xattr->name)) {
+			if (flags & XATTR_CREATE) {
+				xattr = new_xattr;
+				err = -EEXIST;
+			} else if (new_xattr) {
+				list_replace(&xattr->list, &new_xattr->list);
+			} else {
+				list_del(&xattr->list);
+			}
+			goto out;
+		}
+	}
+	if (flags & XATTR_REPLACE) {
+		xattr = new_xattr;
+		err = -ENODATA;
+	} else {
+		list_add(&new_xattr->list, &xattrs->head);
+		xattr = NULL;
+	}
+out:
+	spin_unlock(&xattrs->lock);
+	if (xattr) {
+		kfree(xattr->name);
+		kfree(xattr);
+	}
+	return err;
+
+}
+
+/**
+ * simple_xattr_set - xattr SET operation for in-memory/pseudo filesystems
+ * @xattrs: target simple_xattr list
+ * @name: name of the new extended attribute
+ * @value: value of the new xattr. If %NULL, will remove the attribute
+ * @size: size of the new xattr
+ * @flags: %XATTR_{CREATE|REPLACE}
+ *
+ * %XATTR_CREATE is set, the xattr shouldn't exist already; otherwise fails
+ * with -EEXIST.  If %XATTR_REPLACE is set, the xattr should exist;
+ * otherwise, fails with -ENODATA.
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
+		     const void *value, size_t size, int flags)
+{
+	if (size == 0)
+		value = ""; /* empty EA, do not remove */
+	return __simple_xattr_set(xattrs, name, value, size, flags);
+}
+
+/*
+ * xattr REMOVE operation for in-memory/pseudo filesystems
+ */
+int simple_xattr_remove(struct simple_xattrs *xattrs, const char *name)
+{
+	return __simple_xattr_set(xattrs, name, NULL, 0, XATTR_REPLACE);
+}
+
+static bool xattr_is_trusted(const char *name)
+{
+	return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
+}
+
+/*
+ * xattr LIST operation for in-memory/pseudo filesystems
+ */
+ssize_t simple_xattr_list(struct simple_xattrs *xattrs, char *buffer,
+			  size_t size)
+{
+	bool trusted = capable(CAP_SYS_ADMIN);
+	struct simple_xattr *xattr;
+	size_t used = 0;
+
+	spin_lock(&xattrs->lock);
+	list_for_each_entry(xattr, &xattrs->head, list) {
+		size_t len;
+
+		/* skip "trusted." attributes for unprivileged callers */
+		if (!trusted && xattr_is_trusted(xattr->name))
+			continue;
+
+		len = strlen(xattr->name) + 1;
+		used += len;
+		if (buffer) {
+			if (size < used) {
+				used = -ERANGE;
+				break;
+			}
+			memcpy(buffer, xattr->name, len);
+			buffer += len;
+		}
+	}
+	spin_unlock(&xattrs->lock);
+
+	return used;
+}
+
+/*
+ * Adds an extended attribute to the list
+ */
+void simple_xattr_list_add(struct simple_xattrs *xattrs,
+			   struct simple_xattr *new_xattr)
+{
+	spin_lock(&xattrs->lock);
+	list_add(&new_xattr->list, &xattrs->head);
+	spin_unlock(&xattrs->lock);
+}

include/linux/cgroup.h

@@ -17,6 +17,7 @@
 #include <linux/rwsem.h>
 #include <linux/idr.h>
 #include <linux/workqueue.h>
+#include <linux/xattr.h>
 
 #ifdef CONFIG_CGROUPS
 
@@ -45,17 +46,13 @@ extern const struct file_operations proc_cgroup_operations;
 
 /* Define the enumeration of all builtin cgroup subsystems */
 #define SUBSYS(_x) _x ## _subsys_id,
+#define IS_SUBSYS_ENABLED(option) IS_ENABLED(option)
 enum cgroup_subsys_id {
 #include <linux/cgroup_subsys.h>
-	CGROUP_BUILTIN_SUBSYS_COUNT
+	CGROUP_SUBSYS_COUNT,
 };
+#undef IS_SUBSYS_ENABLED
 #undef SUBSYS
-/*
- * This define indicates the maximum number of subsystems that can be loaded
- * at once. We limit to this many since cgroupfs_root has subsys_bits to keep
- * track of all of them.
- */
-#define CGROUP_SUBSYS_COUNT (BITS_PER_BYTE*sizeof(unsigned long))
 
 /* Per-subsystem/per-cgroup state maintained by the system. */
 struct cgroup_subsys_state {
@@ -216,6 +213,9 @@ struct cgroup {
 	/* List of events which userspace want to receive */
 	struct list_head event_list;
 	spinlock_t event_list_lock;
+
+	/* directory xattrs */
+	struct simple_xattrs xattrs;
 };
 
 /*
@@ -309,6 +309,9 @@ struct cftype {
 	/* CFTYPE_* flags */
 	unsigned int flags;
 
+	/* file xattrs */
+	struct simple_xattrs xattrs;
+
 	int (*open)(struct inode *inode, struct file *file);
 	ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft,
 			struct file *file,
@@ -394,7 +397,7 @@ struct cftype {
  */
 struct cftype_set {
 	struct list_head		node;	/* chained at subsys->cftsets */
-	const struct cftype		*cfts;
+	struct cftype			*cfts;
 };
 
 struct cgroup_scanner {
@@ -406,8 +409,8 @@ struct cgroup_scanner {
 	void *data;
 };
 
-int cgroup_add_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts);
-int cgroup_rm_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts);
+int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
+int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
 
 int cgroup_is_removed(const struct cgroup *cgrp);
 
@@ -521,7 +524,9 @@ struct cgroup_subsys {
 };
 
 #define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys;
+#define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option)
 #include <linux/cgroup_subsys.h>
+#undef IS_SUBSYS_ENABLED
 #undef SUBSYS
 
 static inline struct cgroup_subsys_state *cgroup_subsys_state(

include/linux/cgroup_subsys.h

@@ -7,73 +7,73 @@
 
 /* */
 
-#ifdef CONFIG_CPUSETS
+#if IS_SUBSYS_ENABLED(CONFIG_CPUSETS)
 SUBSYS(cpuset)
 #endif
 
 /* */
 
-#ifdef CONFIG_CGROUP_DEBUG
+#if IS_SUBSYS_ENABLED(CONFIG_CGROUP_DEBUG)
 SUBSYS(debug)
 #endif
 
 /* */
 
-#ifdef CONFIG_CGROUP_SCHED
+#if IS_SUBSYS_ENABLED(CONFIG_CGROUP_SCHED)
 SUBSYS(cpu_cgroup)
 #endif
 
 /* */
 
-#ifdef CONFIG_CGROUP_CPUACCT
+#if IS_SUBSYS_ENABLED(CONFIG_CGROUP_CPUACCT)
 SUBSYS(cpuacct)
 #endif
 
 /* */
 
-#ifdef CONFIG_MEMCG
+#if IS_SUBSYS_ENABLED(CONFIG_MEMCG)
 SUBSYS(mem_cgroup)
 #endif
 
 /* */
 
-#ifdef CONFIG_CGROUP_DEVICE
+#if IS_SUBSYS_ENABLED(CONFIG_CGROUP_DEVICE)
 SUBSYS(devices)
 #endif
 
 /* */
 
-#ifdef CONFIG_CGROUP_FREEZER
+#if IS_SUBSYS_ENABLED(CONFIG_CGROUP_FREEZER)
 SUBSYS(freezer)
 #endif
 
 /* */
 
-#ifdef CONFIG_NET_CLS_CGROUP
+#if IS_SUBSYS_ENABLED(CONFIG_NET_CLS_CGROUP)
 SUBSYS(net_cls)
 #endif
 
 /* */
 
-#ifdef CONFIG_BLK_CGROUP
+#if IS_SUBSYS_ENABLED(CONFIG_BLK_CGROUP)
 SUBSYS(blkio)
 #endif
 
 /* */
 
-#ifdef CONFIG_CGROUP_PERF
+#if IS_SUBSYS_ENABLED(CONFIG_CGROUP_PERF)
 SUBSYS(perf)
 #endif
 
 /* */
 
-#ifdef CONFIG_NETPRIO_CGROUP
+#if IS_SUBSYS_ENABLED(CONFIG_NETPRIO_CGROUP)
 SUBSYS(net_prio)
 #endif
 
 /* */
 
-#ifdef CONFIG_CGROUP_HUGETLB
+#if IS_SUBSYS_ENABLED(CONFIG_CGROUP_HUGETLB)
 SUBSYS(hugetlb)
 #endif
 

include/linux/shmem_fs.h

@@ -5,6 +5,7 @@
 #include <linux/mempolicy.h>
 #include <linux/pagemap.h>
 #include <linux/percpu_counter.h>
+#include <linux/xattr.h>
 
 /* inode in-kernel data */
 
@@ -18,7 +19,7 @@ struct shmem_inode_info {
 	};
 	struct shared_policy	policy;		/* NUMA memory alloc policy */
 	struct list_head	swaplist;	/* chain of maybes on swap */
-	struct list_head	xattr_list;	/* list of shmem_xattr */
+	struct simple_xattrs	xattrs;		/* list of xattrs */
 	struct inode		vfs_inode;
 };
 

include/linux/xattr.h

@@ -59,7 +59,9 @@
 
 #ifdef  __KERNEL__
 
+#include <linux/slab.h>
 #include <linux/types.h>
+#include <linux/spinlock.h>
 
 struct inode;
 struct dentry;
@@ -96,6 +98,52 @@ ssize_t vfs_getxattr_alloc(struct dentry *dentry, const char *name,
 			   char **xattr_value, size_t size, gfp_t flags);
 int vfs_xattr_cmp(struct dentry *dentry, const char *xattr_name,
 		  const char *value, size_t size, gfp_t flags);
+
+struct simple_xattrs {
+	struct list_head head;
+	spinlock_t lock;
+};
+
+struct simple_xattr {
+	struct list_head list;
+	char *name;
+	size_t size;
+	char value[0];
+};
+
+/*
+ * initialize the simple_xattrs structure
+ */
+static inline void simple_xattrs_init(struct simple_xattrs *xattrs)
+{
+	INIT_LIST_HEAD(&xattrs->head);
+	spin_lock_init(&xattrs->lock);
+}
+
+/*
+ * free all the xattrs
+ */
+static inline void simple_xattrs_free(struct simple_xattrs *xattrs)
+{
+	struct simple_xattr *xattr, *node;
+
+	list_for_each_entry_safe(xattr, node, &xattrs->head, list) {
+		kfree(xattr->name);
+		kfree(xattr);
+	}
+}
+
+struct simple_xattr *simple_xattr_alloc(const void *value, size_t size);
+int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
+		     void *buffer, size_t size);
+int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
+		     const void *value, size_t size, int flags);
+int simple_xattr_remove(struct simple_xattrs *xattrs, const char *name);
+ssize_t simple_xattr_list(struct simple_xattrs *xattrs, char *buffer,
+			  size_t size);
+void simple_xattr_list_add(struct simple_xattrs *xattrs,
+			   struct simple_xattr *new_xattr);
+
 #endif  /*  __KERNEL__  */
 
 #endif	/* _LINUX_XATTR_H */

include/net/cls_cgroup.h

@@ -17,14 +17,16 @@
 #include <linux/hardirq.h>
 #include <linux/rcupdate.h>
 
-#ifdef CONFIG_CGROUPS
+#if IS_ENABLED(CONFIG_NET_CLS_CGROUP)
 struct cgroup_cls_state
 {
 	struct cgroup_subsys_state css;
 	u32 classid;
 };
 
-#ifdef CONFIG_NET_CLS_CGROUP
+extern void sock_update_classid(struct sock *sk);
+
+#if IS_BUILTIN(CONFIG_NET_CLS_CGROUP)
 static inline u32 task_cls_classid(struct task_struct *p)
 {
 	int classid;
@@ -39,32 +41,33 @@ static inline u32 task_cls_classid(struct task_struct *p)
 
 	return classid;
 }
-#else
-extern int net_cls_subsys_id;
-
+#elif IS_MODULE(CONFIG_NET_CLS_CGROUP)
 static inline u32 task_cls_classid(struct task_struct *p)
 {
-	int id;
+	struct cgroup_subsys_state *css;
 	u32 classid = 0;
 
 	if (in_interrupt())
 		return 0;
 
 	rcu_read_lock();
-	id = rcu_dereference_index_check(net_cls_subsys_id,
-					 rcu_read_lock_held());
-	if (id >= 0)
-		classid = container_of(task_subsys_state(p, id),
+	css = task_subsys_state(p, net_cls_subsys_id);
+	if (css)
+		classid = container_of(css,
 				       struct cgroup_cls_state, css)->classid;
 	rcu_read_unlock();
 
 	return classid;
 }
 #endif
-#else
+#else /* !CGROUP_NET_CLS_CGROUP */
+static inline void sock_update_classid(struct sock *sk)
+{
+}
+
 static inline u32 task_cls_classid(struct task_struct *p)
 {
 	return 0;
 }
-#endif
+#endif /* CGROUP_NET_CLS_CGROUP */
 #endif  /* _NET_CLS_CGROUP_H */

include/net/netprio_cgroup.h

@@ -18,23 +18,18 @@
 #include <linux/rcupdate.h>
 
 
+#if IS_ENABLED(CONFIG_NETPRIO_CGROUP)
 struct netprio_map {
 	struct rcu_head rcu;
 	u32 priomap_len;
 	u32 priomap[];
 };
 
-#ifdef CONFIG_CGROUPS
-
 struct cgroup_netprio_state {
 	struct cgroup_subsys_state css;
 	u32 prioidx;
 };
 
-#ifndef CONFIG_NETPRIO_CGROUP
-extern int net_prio_subsys_id;
-#endif
-
 extern void sock_update_netprioidx(struct sock *sk, struct task_struct *task);
 
 #if IS_BUILTIN(CONFIG_NETPRIO_CGROUP)
@@ -56,33 +51,28 @@ static inline u32 task_netprioidx(struct task_struct *p)
 
 static inline u32 task_netprioidx(struct task_struct *p)
 {
-	struct cgroup_netprio_state *state;
-	int subsys_id;
+	struct cgroup_subsys_state *css;
 	u32 idx = 0;
 
 	rcu_read_lock();
-	subsys_id = rcu_dereference_index_check(net_prio_subsys_id,
-						rcu_read_lock_held());
-	if (subsys_id >= 0) {
-		state = container_of(task_subsys_state(p, subsys_id),
-				     struct cgroup_netprio_state, css);
-		idx = state->prioidx;
-	}
+	css = task_subsys_state(p, net_prio_subsys_id);
+	if (css)
+		idx = container_of(css,
+				   struct cgroup_netprio_state, css)->prioidx;
 	rcu_read_unlock();
 	return idx;
 }
+#endif
 
-#else
+#else /* !CONFIG_NETPRIO_CGROUP */
 
 static inline u32 task_netprioidx(struct task_struct *p)
 {
 	return 0;
 }
 
-#endif /* CONFIG_NETPRIO_CGROUP */
-
-#else
 #define sock_update_netprioidx(sk, task)
-#endif
+
+#endif /* CONFIG_NETPRIO_CGROUP */
 
 #endif  /* _NET_CLS_CGROUP_H */

include/net/sock.h

@@ -1486,14 +1486,6 @@ extern void *sock_kmalloc(struct sock *sk, int size,
 extern void sock_kfree_s(struct sock *sk, void *mem, int size);
 extern void sk_send_sigurg(struct sock *sk);
 
-#ifdef CONFIG_CGROUPS
-extern void sock_update_classid(struct sock *sk);
-#else
-static inline void sock_update_classid(struct sock *sk)
-{
-}
-#endif
-
 /*
  * Functions to fill in entries in struct proto_ops when a protocol
  * does not implement a particular function.

kernel/cgroup.c

@@ -88,11 +88,12 @@ static DEFINE_MUTEX(cgroup_root_mutex);
 
 /*
  * Generate an array of cgroup subsystem pointers. At boot time, this is
- * populated up to CGROUP_BUILTIN_SUBSYS_COUNT, and modular subsystems are
+ * populated with the built in subsystems, and modular subsystems are
  * registered after that. The mutable section of this array is protected by
  * cgroup_mutex.
  */
-#define SUBSYS(_x) &_x ## _subsys,
+#define SUBSYS(_x) [_x ## _subsys_id] = &_x ## _subsys,
+#define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option)
 static struct cgroup_subsys *subsys[CGROUP_SUBSYS_COUNT] = {
 #include <linux/cgroup_subsys.h>
 };
@@ -111,13 +112,13 @@ struct cgroupfs_root {
 	 * The bitmask of subsystems intended to be attached to this
 	 * hierarchy
 	 */
-	unsigned long subsys_bits;
+	unsigned long subsys_mask;
 
 	/* Unique id for this hierarchy. */
 	int hierarchy_id;
 
 	/* The bitmask of subsystems currently attached to this hierarchy */
-	unsigned long actual_subsys_bits;
+	unsigned long actual_subsys_mask;
 
 	/* A list running through the attached subsystems */
 	struct list_head subsys_list;
@@ -276,7 +277,8 @@ inline int cgroup_is_removed(const struct cgroup *cgrp)
 
 /* bits in struct cgroupfs_root flags field */
 enum {
-	ROOT_NOPREFIX, /* mounted subsystems have no named prefix */
+	ROOT_NOPREFIX,	/* mounted subsystems have no named prefix */
+	ROOT_XATTR,	/* supports extended attributes */
 };
 
 static int cgroup_is_releasable(const struct cgroup *cgrp)
@@ -556,7 +558,7 @@ static struct css_set *find_existing_css_set(
 	 * won't change, so no need for locking.
 	 */
 	for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
-		if (root->subsys_bits & (1UL << i)) {
+		if (root->subsys_mask & (1UL << i)) {
 			/* Subsystem is in this hierarchy. So we want
 			 * the subsystem state from the new
 			 * cgroup */
@@ -824,7 +826,8 @@ EXPORT_SYMBOL_GPL(cgroup_unlock);
 static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode);
 static struct dentry *cgroup_lookup(struct inode *, struct dentry *, unsigned int);
 static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry);
-static int cgroup_populate_dir(struct cgroup *cgrp);
+static int cgroup_populate_dir(struct cgroup *cgrp, bool base_files,
+			       unsigned long subsys_mask);
 static const struct inode_operations cgroup_dir_inode_operations;
 static const struct file_operations proc_cgroupstats_operations;
 
@@ -912,15 +915,19 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
 		 */
 		BUG_ON(!list_empty(&cgrp->pidlists));
 
+		simple_xattrs_free(&cgrp->xattrs);
+
 		kfree_rcu(cgrp, rcu_head);
 	} else {
 		struct cfent *cfe = __d_cfe(dentry);
 		struct cgroup *cgrp = dentry->d_parent->d_fsdata;
+		struct cftype *cft = cfe->type;
 
 		WARN_ONCE(!list_empty(&cfe->node) &&
 			  cgrp != &cgrp->root->top_cgroup,
 			  "cfe still linked for %s\n", cfe->type->name);
 		kfree(cfe);
+		simple_xattrs_free(&cft->xattrs);
 	}
 	iput(inode);
 }
@@ -963,12 +970,29 @@ static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
 	return -ENOENT;
 }
 
-static void cgroup_clear_directory(struct dentry *dir)
+/**
+ * cgroup_clear_directory - selective removal of base and subsystem files
+ * @dir: directory containing the files
+ * @base_files: true if the base files should be removed
+ * @subsys_mask: mask of the subsystem ids whose files should be removed
+ */
+static void cgroup_clear_directory(struct dentry *dir, bool base_files,
+				   unsigned long subsys_mask)
 {
 	struct cgroup *cgrp = __d_cgrp(dir);
+	struct cgroup_subsys *ss;
 
-	while (!list_empty(&cgrp->files))
-		cgroup_rm_file(cgrp, NULL);
+	for_each_subsys(cgrp->root, ss) {
+		struct cftype_set *set;
+		if (!test_bit(ss->subsys_id, &subsys_mask))
+			continue;
+		list_for_each_entry(set, &ss->cftsets, node)
+			cgroup_rm_file(cgrp, set->cfts);
+	}
+	if (base_files) {
+		while (!list_empty(&cgrp->files))
+			cgroup_rm_file(cgrp, NULL);
+	}
 }
 
 /*
@@ -977,8 +1001,9 @@ static void cgroup_clear_directory(struct dentry *dir)
 static void cgroup_d_remove_dir(struct dentry *dentry)
 {
 	struct dentry *parent;
+	struct cgroupfs_root *root = dentry->d_sb->s_fs_info;
 
-	cgroup_clear_directory(dentry);
+	cgroup_clear_directory(dentry, true, root->subsys_mask);
 
 	parent = dentry->d_parent;
 	spin_lock(&parent->d_lock);
@@ -1022,22 +1047,22 @@ void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css)
  * returns an error, no reference counts are touched.
  */
 static int rebind_subsystems(struct cgroupfs_root *root,
-			      unsigned long final_bits)
+			      unsigned long final_subsys_mask)
 {
-	unsigned long added_bits, removed_bits;
+	unsigned long added_mask, removed_mask;
 	struct cgroup *cgrp = &root->top_cgroup;
 	int i;
 
 	BUG_ON(!mutex_is_locked(&cgroup_mutex));
 	BUG_ON(!mutex_is_locked(&cgroup_root_mutex));
 
-	removed_bits = root->actual_subsys_bits & ~final_bits;
-	added_bits = final_bits & ~root->actual_subsys_bits;
+	removed_mask = root->actual_subsys_mask & ~final_subsys_mask;
+	added_mask = final_subsys_mask & ~root->actual_subsys_mask;
 	/* Check that any added subsystems are currently free */
 	for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
 		unsigned long bit = 1UL << i;
 		struct cgroup_subsys *ss = subsys[i];
-		if (!(bit & added_bits))
+		if (!(bit & added_mask))
 			continue;
 		/*
 		 * Nobody should tell us to do a subsys that doesn't exist:
@@ -1062,7 +1087,7 @@ static int rebind_subsystems(struct cgroupfs_root *root,
 	for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
 		struct cgroup_subsys *ss = subsys[i];
 		unsigned long bit = 1UL << i;
-		if (bit & added_bits) {
+		if (bit & added_mask) {
 			/* We're binding this subsystem to this hierarchy */
 			BUG_ON(ss == NULL);
 			BUG_ON(cgrp->subsys[i]);
@@ -1075,7 +1100,7 @@ static int rebind_subsystems(struct cgroupfs_root *root,
 			if (ss->bind)
 				ss->bind(cgrp);
 			/* refcount was already taken, and we're keeping it */
-		} else if (bit & removed_bits) {
+		} else if (bit & removed_mask) {
 			/* We're removing this subsystem */
 			BUG_ON(ss == NULL);
 			BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]);
@@ -1088,7 +1113,7 @@ static int rebind_subsystems(struct cgroupfs_root *root,
 			list_move(&ss->sibling, &rootnode.subsys_list);
 			/* subsystem is now free - drop reference on module */
 			module_put(ss->module);
-		} else if (bit & final_bits) {
+		} else if (bit & final_subsys_mask) {
 			/* Subsystem state should already exist */
 			BUG_ON(ss == NULL);
 			BUG_ON(!cgrp->subsys[i]);
@@ -1105,7 +1130,7 @@ static int rebind_subsystems(struct cgroupfs_root *root,
 			BUG_ON(cgrp->subsys[i]);
 		}
 	}
-	root->subsys_bits = root->actual_subsys_bits = final_bits;
+	root->subsys_mask = root->actual_subsys_mask = final_subsys_mask;
 	synchronize_rcu();
 
 	return 0;
@@ -1121,6 +1146,8 @@ static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry)
 		seq_printf(seq, ",%s", ss->name);
 	if (test_bit(ROOT_NOPREFIX, &root->flags))
 		seq_puts(seq, ",noprefix");
+	if (test_bit(ROOT_XATTR, &root->flags))
+		seq_puts(seq, ",xattr");
 	if (strlen(root->release_agent_path))
 		seq_printf(seq, ",release_agent=%s", root->release_agent_path);
 	if (clone_children(&root->top_cgroup))
@@ -1132,7 +1159,7 @@ static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry)
 }
 
 struct cgroup_sb_opts {
-	unsigned long subsys_bits;
+	unsigned long subsys_mask;
 	unsigned long flags;
 	char *release_agent;
 	bool clone_children;
@@ -1189,6 +1216,10 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 			opts->clone_children = true;
 			continue;
 		}
+		if (!strcmp(token, "xattr")) {
+			set_bit(ROOT_XATTR, &opts->flags);
+			continue;
+		}
 		if (!strncmp(token, "release_agent=", 14)) {
 			/* Specifying two release agents is forbidden */
 			if (opts->release_agent)
@@ -1237,7 +1268,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 			/* Mutually exclusive option 'all' + subsystem name */
 			if (all_ss)
 				return -EINVAL;
-			set_bit(i, &opts->subsys_bits);
+			set_bit(i, &opts->subsys_mask);
 			one_ss = true;
 
 			break;
@@ -1258,7 +1289,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 				continue;
 			if (ss->disabled)
 				continue;
-			set_bit(i, &opts->subsys_bits);
+			set_bit(i, &opts->subsys_mask);
 		}
 	}
 
@@ -1270,19 +1301,19 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 	 * the cpuset subsystem.
 	 */
 	if (test_bit(ROOT_NOPREFIX, &opts->flags) &&
-	    (opts->subsys_bits & mask))
+	    (opts->subsys_mask & mask))
 		return -EINVAL;
 
 
 	/* Can't specify "none" and some subsystems */
-	if (opts->subsys_bits && opts->none)
+	if (opts->subsys_mask && opts->none)
 		return -EINVAL;
 
 	/*
 	 * We either have to specify by name or by subsystems. (So all
 	 * empty hierarchies must have a name).
 	 */
-	if (!opts->subsys_bits && !opts->name)
+	if (!opts->subsys_mask && !opts->name)
 		return -EINVAL;
 
 	/*
@@ -1291,10 +1322,10 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 	 * take duplicate reference counts on a subsystem that's already used,
 	 * but rebind_subsystems handles this case.
 	 */
-	for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) {
+	for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
 		unsigned long bit = 1UL << i;
 
-		if (!(bit & opts->subsys_bits))
+		if (!(bit & opts->subsys_mask))
 			continue;
 		if (!try_module_get(subsys[i]->module)) {
 			module_pin_failed = true;
@@ -1307,11 +1338,11 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 		 * raced with a module_delete call, and to the user this is
 		 * essentially a "subsystem doesn't exist" case.
 		 */
-		for (i--; i >= CGROUP_BUILTIN_SUBSYS_COUNT; i--) {
+		for (i--; i >= 0; i--) {
 			/* drop refcounts only on the ones we took */
 			unsigned long bit = 1UL << i;
 
-			if (!(bit & opts->subsys_bits))
+			if (!(bit & opts->subsys_mask))
 				continue;
 			module_put(subsys[i]->module);
 		}
@@ -1321,13 +1352,13 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 	return 0;
 }
 
-static void drop_parsed_module_refcounts(unsigned long subsys_bits)
+static void drop_parsed_module_refcounts(unsigned long subsys_mask)
 {
 	int i;
-	for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) {
+	for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
 		unsigned long bit = 1UL << i;
 
-		if (!(bit & subsys_bits))
+		if (!(bit & subsys_mask))
 			continue;
 		module_put(subsys[i]->module);
 	}
@@ -1339,6 +1370,7 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data)
 	struct cgroupfs_root *root = sb->s_fs_info;
 	struct cgroup *cgrp = &root->top_cgroup;
 	struct cgroup_sb_opts opts;
+	unsigned long added_mask, removed_mask;
 
 	mutex_lock(&cgrp->dentry->d_inode->i_mutex);
 	mutex_lock(&cgroup_mutex);
@@ -1350,27 +1382,31 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data)
 		goto out_unlock;
 
 	/* See feature-removal-schedule.txt */
-	if (opts.subsys_bits != root->actual_subsys_bits || opts.release_agent)
+	if (opts.subsys_mask != root->actual_subsys_mask || opts.release_agent)
 		pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n",
 			   task_tgid_nr(current), current->comm);
 
+	added_mask = opts.subsys_mask & ~root->subsys_mask;
+	removed_mask = root->subsys_mask & ~opts.subsys_mask;
+
 	/* Don't allow flags or name to change at remount */
 	if (opts.flags != root->flags ||
 	    (opts.name && strcmp(opts.name, root->name))) {
 		ret = -EINVAL;
-		drop_parsed_module_refcounts(opts.subsys_bits);
+		drop_parsed_module_refcounts(opts.subsys_mask);
 		goto out_unlock;
 	}
 
-	ret = rebind_subsystems(root, opts.subsys_bits);
+	ret = rebind_subsystems(root, opts.subsys_mask);
 	if (ret) {
-		drop_parsed_module_refcounts(opts.subsys_bits);
+		drop_parsed_module_refcounts(opts.subsys_mask);
 		goto out_unlock;
 	}
 
 	/* clear out any existing files and repopulate subsystem files */
-	cgroup_clear_directory(cgrp->dentry);
-	cgroup_populate_dir(cgrp);
+	cgroup_clear_directory(cgrp->dentry, false, removed_mask);
+	/* re-populate subsystem files */
+	cgroup_populate_dir(cgrp, false, added_mask);
 
 	if (opts.release_agent)
 		strcpy(root->release_agent_path, opts.release_agent);
@@ -1401,6 +1437,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
 	mutex_init(&cgrp->pidlist_mutex);
 	INIT_LIST_HEAD(&cgrp->event_list);
 	spin_lock_init(&cgrp->event_list_lock);
+	simple_xattrs_init(&cgrp->xattrs);
 }
 
 static void init_cgroup_root(struct cgroupfs_root *root)
@@ -1455,8 +1492,8 @@ static int cgroup_test_super(struct super_block *sb, void *data)
 	 * If we asked for subsystems (or explicitly for no
 	 * subsystems) then they must match
 	 */
-	if ((opts->subsys_bits || opts->none)
-	    && (opts->subsys_bits != root->subsys_bits))
+	if ((opts->subsys_mask || opts->none)
+	    && (opts->subsys_mask != root->subsys_mask))
 		return 0;
 
 	return 1;
@@ -1466,7 +1503,7 @@ static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts)
 {
 	struct cgroupfs_root *root;
 
-	if (!opts->subsys_bits && !opts->none)
+	if (!opts->subsys_mask && !opts->none)
 		return NULL;
 
 	root = kzalloc(sizeof(*root), GFP_KERNEL);
@@ -1479,7 +1516,7 @@ static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts)
 	}
 	init_cgroup_root(root);
 
-	root->subsys_bits = opts->subsys_bits;
+	root->subsys_mask = opts->subsys_mask;
 	root->flags = opts->flags;
 	if (opts->release_agent)
 		strcpy(root->release_agent_path, opts->release_agent);
@@ -1511,7 +1548,7 @@ static int cgroup_set_super(struct super_block *sb, void *data)
 	if (!opts->new_root)
 		return -EINVAL;
 
-	BUG_ON(!opts->subsys_bits && !opts->none);
+	BUG_ON(!opts->subsys_mask && !opts->none);
 
 	ret = set_anon_super(sb, NULL);
 	if (ret)
@@ -1629,7 +1666,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
 		if (ret)
 			goto unlock_drop;
 
-		ret = rebind_subsystems(root, root->subsys_bits);
+		ret = rebind_subsystems(root, root->subsys_mask);
 		if (ret == -EBUSY) {
 			free_cg_links(&tmp_cg_links);
 			goto unlock_drop;
@@ -1669,7 +1706,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
 		BUG_ON(root->number_of_cgroups != 1);
 
 		cred = override_creds(&init_cred);
-		cgroup_populate_dir(root_cgrp);
+		cgroup_populate_dir(root_cgrp, true, root->subsys_mask);
 		revert_creds(cred);
 		mutex_unlock(&cgroup_root_mutex);
 		mutex_unlock(&cgroup_mutex);
@@ -1681,7 +1718,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
 		 */
 		cgroup_drop_root(opts.new_root);
 		/* no subsys rebinding, so refcounts don't change */
-		drop_parsed_module_refcounts(opts.subsys_bits);
+		drop_parsed_module_refcounts(opts.subsys_mask);
 	}
 
 	kfree(opts.release_agent);
@@ -1695,7 +1732,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
  drop_new_super:
 	deactivate_locked_super(sb);
  drop_modules:
-	drop_parsed_module_refcounts(opts.subsys_bits);
+	drop_parsed_module_refcounts(opts.subsys_mask);
  out_err:
 	kfree(opts.release_agent);
 	kfree(opts.name);
@@ -1745,6 +1782,8 @@ static void cgroup_kill_sb(struct super_block *sb) {
 	mutex_unlock(&cgroup_root_mutex);
 	mutex_unlock(&cgroup_mutex);
 
+	simple_xattrs_free(&cgrp->xattrs);
+
 	kill_litter_super(sb);
 	cgroup_drop_root(root);
 }
@@ -2551,6 +2590,64 @@ static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry,
 	return simple_rename(old_dir, old_dentry, new_dir, new_dentry);
 }
 
+static struct simple_xattrs *__d_xattrs(struct dentry *dentry)
+{
+	if (S_ISDIR(dentry->d_inode->i_mode))
+		return &__d_cgrp(dentry)->xattrs;
+	else
+		return &__d_cft(dentry)->xattrs;
+}
+
+static inline int xattr_enabled(struct dentry *dentry)
+{
+	struct cgroupfs_root *root = dentry->d_sb->s_fs_info;
+	return test_bit(ROOT_XATTR, &root->flags);
+}
+
+static bool is_valid_xattr(const char *name)
+{
+	if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
+	    !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN))
+		return true;
+	return false;
+}
+
+static int cgroup_setxattr(struct dentry *dentry, const char *name,
+			   const void *val, size_t size, int flags)
+{
+	if (!xattr_enabled(dentry))
+		return -EOPNOTSUPP;
+	if (!is_valid_xattr(name))
+		return -EINVAL;
+	return simple_xattr_set(__d_xattrs(dentry), name, val, size, flags);
+}
+
+static int cgroup_removexattr(struct dentry *dentry, const char *name)
+{
+	if (!xattr_enabled(dentry))
+		return -EOPNOTSUPP;
+	if (!is_valid_xattr(name))
+		return -EINVAL;
+	return simple_xattr_remove(__d_xattrs(dentry), name);
+}
+
+static ssize_t cgroup_getxattr(struct dentry *dentry, const char *name,
+			       void *buf, size_t size)
+{
+	if (!xattr_enabled(dentry))
+		return -EOPNOTSUPP;
+	if (!is_valid_xattr(name))
+		return -EINVAL;
+	return simple_xattr_get(__d_xattrs(dentry), name, buf, size);
+}
+
+static ssize_t cgroup_listxattr(struct dentry *dentry, char *buf, size_t size)
+{
+	if (!xattr_enabled(dentry))
+		return -EOPNOTSUPP;
+	return simple_xattr_list(__d_xattrs(dentry), buf, size);
+}
+
 static const struct file_operations cgroup_file_operations = {
 	.read = cgroup_file_read,
 	.write = cgroup_file_write,
@@ -2559,11 +2656,22 @@ static const struct file_operations cgroup_file_operations = {
 	.release = cgroup_file_release,
 };
 
+static const struct inode_operations cgroup_file_inode_operations = {
+	.setxattr = cgroup_setxattr,
+	.getxattr = cgroup_getxattr,
+	.listxattr = cgroup_listxattr,
+	.removexattr = cgroup_removexattr,
+};
+
 static const struct inode_operations cgroup_dir_inode_operations = {
 	.lookup = cgroup_lookup,
 	.mkdir = cgroup_mkdir,
 	.rmdir = cgroup_rmdir,
 	.rename = cgroup_rename,
+	.setxattr = cgroup_setxattr,
+	.getxattr = cgroup_getxattr,
+	.listxattr = cgroup_listxattr,
+	.removexattr = cgroup_removexattr,
 };
 
 static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
@@ -2611,6 +2719,7 @@ static int cgroup_create_file(struct dentry *dentry, umode_t mode,
 	} else if (S_ISREG(mode)) {
 		inode->i_size = 0;
 		inode->i_fop = &cgroup_file_operations;
+		inode->i_op = &cgroup_file_inode_operations;
 	}
 	d_instantiate(dentry, inode);
 	dget(dentry);	/* Extra count - pin the dentry in core */
@@ -2671,7 +2780,7 @@ static umode_t cgroup_file_mode(const struct cftype *cft)
 }
 
 static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
-			   const struct cftype *cft)
+			   struct cftype *cft)
 {
 	struct dentry *dir = cgrp->dentry;
 	struct cgroup *parent = __d_cgrp(dir);
@@ -2681,6 +2790,8 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
 	umode_t mode;
 	char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 };
 
+	simple_xattrs_init(&cft->xattrs);
+
 	/* does @cft->flags tell us to skip creation on @cgrp? */
 	if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent)
 		return 0;
@@ -2721,9 +2832,9 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
 }
 
 static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys,
-			      const struct cftype cfts[], bool is_add)
+			      struct cftype cfts[], bool is_add)
 {
-	const struct cftype *cft;
+	struct cftype *cft;
 	int err, ret = 0;
 
 	for (cft = cfts; cft->name[0] != '\0'; cft++) {
@@ -2757,7 +2868,7 @@ static void cgroup_cfts_prepare(void)
 }
 
 static void cgroup_cfts_commit(struct cgroup_subsys *ss,
-			       const struct cftype *cfts, bool is_add)
+			       struct cftype *cfts, bool is_add)
 	__releases(&cgroup_mutex) __releases(&cgroup_cft_mutex)
 {
 	LIST_HEAD(pending);
@@ -2808,7 +2919,7 @@ static void cgroup_cfts_commit(struct cgroup_subsys *ss,
  * function currently returns 0 as long as @cfts registration is successful
  * even if some file creation attempts on existing cgroups fail.
  */
-int cgroup_add_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts)
+int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
 {
 	struct cftype_set *set;
 
@@ -2838,7 +2949,7 @@ EXPORT_SYMBOL_GPL(cgroup_add_cftypes);
  * Returns 0 on successful unregistration, -ENOENT if @cfts is not
  * registered with @ss.
  */
-int cgroup_rm_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts)
+int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
 {
 	struct cftype_set *set;
 
@@ -3843,18 +3954,29 @@ static struct cftype files[] = {
 	{ }	/* terminate */
 };
 
-static int cgroup_populate_dir(struct cgroup *cgrp)
+/**
+ * cgroup_populate_dir - selectively creation of files in a directory
+ * @cgrp: target cgroup
+ * @base_files: true if the base files should be added
+ * @subsys_mask: mask of the subsystem ids whose files should be added
+ */
+static int cgroup_populate_dir(struct cgroup *cgrp, bool base_files,
+			       unsigned long subsys_mask)
 {
 	int err;
 	struct cgroup_subsys *ss;
 
-	err = cgroup_addrm_files(cgrp, NULL, files, true);
-	if (err < 0)
-		return err;
+	if (base_files) {
+		err = cgroup_addrm_files(cgrp, NULL, files, true);
+		if (err < 0)
+			return err;
+	}
 
 	/* process cftsets of each subsystem */
 	for_each_subsys(cgrp->root, ss) {
 		struct cftype_set *set;
+		if (!test_bit(ss->subsys_id, &subsys_mask))
+			continue;
 
 		list_for_each_entry(set, &ss->cftsets, node)
 			cgroup_addrm_files(cgrp, ss, set->cfts, true);
@@ -3988,7 +4110,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
 
 	list_add_tail(&cgrp->allcg_node, &root->allcg_list);
 
-	err = cgroup_populate_dir(cgrp);
+	err = cgroup_populate_dir(cgrp, true, root->subsys_mask);
 	/* If err < 0, we have a half-filled directory - oh well ;) */
 
 	mutex_unlock(&cgroup_mutex);
@@ -4321,8 +4443,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
 	 * since cgroup_init_subsys will have already taken care of it.
 	 */
 	if (ss->module == NULL) {
-		/* a few sanity checks */
-		BUG_ON(ss->subsys_id >= CGROUP_BUILTIN_SUBSYS_COUNT);
+		/* a sanity check */
 		BUG_ON(subsys[ss->subsys_id] != ss);
 		return 0;
 	}
@@ -4330,24 +4451,8 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
 	/* init base cftset */
 	cgroup_init_cftsets(ss);
 
-	/*
-	 * need to register a subsys id before anything else - for example,
-	 * init_cgroup_css needs it.
-	 */
 	mutex_lock(&cgroup_mutex);
-	/* find the first empty slot in the array */
-	for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) {
-		if (subsys[i] == NULL)
-			break;
-	}
-	if (i == CGROUP_SUBSYS_COUNT) {
-		/* maximum number of subsystems already registered! */
-		mutex_unlock(&cgroup_mutex);
-		return -EBUSY;
-	}
-	/* assign ourselves the subsys_id */
-	ss->subsys_id = i;
-	subsys[i] = ss;
+	subsys[ss->subsys_id] = ss;
 
 	/*
 	 * no ss->create seems to need anything important in the ss struct, so
@@ -4356,7 +4461,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
 	css = ss->create(dummytop);
 	if (IS_ERR(css)) {
 		/* failure case - need to deassign the subsys[] slot. */
-		subsys[i] = NULL;
+		subsys[ss->subsys_id] = NULL;
 		mutex_unlock(&cgroup_mutex);
 		return PTR_ERR(css);
 	}
@@ -4372,7 +4477,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
 		if (ret) {
 			dummytop->subsys[ss->subsys_id] = NULL;
 			ss->destroy(dummytop);
-			subsys[i] = NULL;
+			subsys[ss->subsys_id] = NULL;
 			mutex_unlock(&cgroup_mutex);
 			return ret;
 		}
@@ -4439,7 +4544,6 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss)
 
 	mutex_lock(&cgroup_mutex);
 	/* deassign the subsys_id */
-	BUG_ON(ss->subsys_id < CGROUP_BUILTIN_SUBSYS_COUNT);
 	subsys[ss->subsys_id] = NULL;
 
 	/* remove subsystem from rootnode's list of subsystems */
@@ -4502,10 +4606,13 @@ int __init cgroup_init_early(void)
 	for (i = 0; i < CSS_SET_TABLE_SIZE; i++)
 		INIT_HLIST_HEAD(&css_set_table[i]);
 
-	/* at bootup time, we don't worry about modular subsystems */
-	for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
+	for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
 		struct cgroup_subsys *ss = subsys[i];
 
+		/* at bootup time, we don't worry about modular subsystems */
+		if (!ss || ss->module)
+			continue;
+
 		BUG_ON(!ss->name);
 		BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN);
 		BUG_ON(!ss->create);
@@ -4538,9 +4645,12 @@ int __init cgroup_init(void)
 	if (err)
 		return err;
 
-	/* at bootup time, we don't worry about modular subsystems */
-	for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
+	for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
 		struct cgroup_subsys *ss = subsys[i];
+
+		/* at bootup time, we don't worry about modular subsystems */
+		if (!ss || ss->module)
+			continue;
 		if (!ss->early_init)
 			cgroup_init_subsys(ss);
 		if (ss->use_id)
@@ -4735,13 +4845,16 @@ void cgroup_fork_callbacks(struct task_struct *child)
 {
 	if (need_forkexit_callback) {
 		int i;
-		/*
-		 * forkexit callbacks are only supported for builtin
-		 * subsystems, and the builtin section of the subsys array is
-		 * immutable, so we don't need to lock the subsys array here.
-		 */
-		for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
+		for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
 			struct cgroup_subsys *ss = subsys[i];
+
+			/*
+			 * forkexit callbacks are only supported for
+			 * builtin subsystems.
+			 */
+			if (!ss || ss->module)
+				continue;
+
 			if (ss->fork)
 				ss->fork(child);
 		}
@@ -4846,12 +4959,13 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks)
 	tsk->cgroups = &init_css_set;
 
 	if (run_callbacks && need_forkexit_callback) {
-		/*
-		 * modular subsystems can't use callbacks, so no need to lock
-		 * the subsys array
-		 */
-		for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
+		for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
 			struct cgroup_subsys *ss = subsys[i];
+
+			/* modular subsystems can't use callbacks */
+			if (!ss || ss->module)
+				continue;
+
 			if (ss->exit) {
 				struct cgroup *old_cgrp =
 					rcu_dereference_raw(cg->subsys[i])->cgroup;
@@ -5037,13 +5151,17 @@ static int __init cgroup_disable(char *str)
 	while ((token = strsep(&str, ",")) != NULL) {
 		if (!*token)
 			continue;
-		/*
-		 * cgroup_disable, being at boot time, can't know about module
-		 * subsystems, so we don't worry about them.
-		 */
-		for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
+		for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
 			struct cgroup_subsys *ss = subsys[i];
 
+			/*
+			 * cgroup_disable, being at boot time, can't
+			 * know about module subsystems, so we don't
+			 * worry about them.
+			 */
+			if (!ss || ss->module)
+				continue;
+
 			if (!strcmp(token, ss->name)) {
 				ss->disabled = 1;
 				printk(KERN_INFO "Disabling %s control group"

mm/shmem.c

@@ -77,13 +77,6 @@ static struct vfsmount *shm_mnt;
 /* Symlink up to this size is kmalloc'ed instead of using a swappable page */
 #define SHORT_SYMLINK_LEN 128
 
-struct shmem_xattr {
-	struct list_head list;	/* anchored by shmem_inode_info->xattr_list */
-	char *name;		/* xattr name */
-	size_t size;
-	char value[0];
-};
-
 /*
  * shmem_fallocate and shmem_writepage communicate via inode->i_private
  * (with i_mutex making sure that it has only one user at a time):
@@ -636,7 +629,6 @@ static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
 static void shmem_evict_inode(struct inode *inode)
 {
 	struct shmem_inode_info *info = SHMEM_I(inode);
-	struct shmem_xattr *xattr, *nxattr;
 
 	if (inode->i_mapping->a_ops == &shmem_aops) {
 		shmem_unacct_size(info->flags, inode->i_size);
@@ -650,10 +642,7 @@ static void shmem_evict_inode(struct inode *inode)
 	} else
 		kfree(info->symlink);
 
-	list_for_each_entry_safe(xattr, nxattr, &info->xattr_list, list) {
-		kfree(xattr->name);
-		kfree(xattr);
-	}
+	simple_xattrs_free(&info->xattrs);
 	BUG_ON(inode->i_blocks);
 	shmem_free_inode(inode->i_sb);
 	clear_inode(inode);
@@ -1377,7 +1366,7 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
 		spin_lock_init(&info->lock);
 		info->flags = flags & VM_NORESERVE;
 		INIT_LIST_HEAD(&info->swaplist);
-		INIT_LIST_HEAD(&info->xattr_list);
+		simple_xattrs_init(&info->xattrs);
 		cache_no_acl(inode);
 
 		switch (mode & S_IFMT) {
@@ -2059,28 +2048,6 @@ static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *co
  * filesystem level, though.
  */
 
-/*
- * Allocate new xattr and copy in the value; but leave the name to callers.
- */
-static struct shmem_xattr *shmem_xattr_alloc(const void *value, size_t size)
-{
-	struct shmem_xattr *new_xattr;
-	size_t len;
-
-	/* wrap around? */
-	len = sizeof(*new_xattr) + size;
-	if (len <= sizeof(*new_xattr))
-		return NULL;
-
-	new_xattr = kmalloc(len, GFP_KERNEL);
-	if (!new_xattr)
-		return NULL;
-
-	new_xattr->size = size;
-	memcpy(new_xattr->value, value, size);
-	return new_xattr;
-}
-
 /*
  * Callback for security_inode_init_security() for acquiring xattrs.
  */
@@ -2090,11 +2057,11 @@ static int shmem_initxattrs(struct inode *inode,
 {
 	struct shmem_inode_info *info = SHMEM_I(inode);
 	const struct xattr *xattr;
-	struct shmem_xattr *new_xattr;
+	struct simple_xattr *new_xattr;
 	size_t len;
 
 	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
-		new_xattr = shmem_xattr_alloc(xattr->value, xattr->value_len);
+		new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
 		if (!new_xattr)
 			return -ENOMEM;
 
@@ -2111,91 +2078,12 @@ static int shmem_initxattrs(struct inode *inode,
 		memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
 		       xattr->name, len);
 
-		spin_lock(&info->lock);
-		list_add(&new_xattr->list, &info->xattr_list);
-		spin_unlock(&info->lock);
+		simple_xattr_list_add(&info->xattrs, new_xattr);
 	}
 
 	return 0;
 }
 
-static int shmem_xattr_get(struct dentry *dentry, const char *name,
-			   void *buffer, size_t size)
-{
-	struct shmem_inode_info *info;
-	struct shmem_xattr *xattr;
-	int ret = -ENODATA;
-
-	info = SHMEM_I(dentry->d_inode);
-
-	spin_lock(&info->lock);
-	list_for_each_entry(xattr, &info->xattr_list, list) {
-		if (strcmp(name, xattr->name))
-			continue;
-
-		ret = xattr->size;
-		if (buffer) {
-			if (size < xattr->size)
-				ret = -ERANGE;
-			else
-				memcpy(buffer, xattr->value, xattr->size);
-		}
-		break;
-	}
-	spin_unlock(&info->lock);
-	return ret;
-}
-
-static int shmem_xattr_set(struct inode *inode, const char *name,
-			   const void *value, size_t size, int flags)
-{
-	struct shmem_inode_info *info = SHMEM_I(inode);
-	struct shmem_xattr *xattr;
-	struct shmem_xattr *new_xattr = NULL;
-	int err = 0;
-
-	/* value == NULL means remove */
-	if (value) {
-		new_xattr = shmem_xattr_alloc(value, size);
-		if (!new_xattr)
-			return -ENOMEM;
-
-		new_xattr->name = kstrdup(name, GFP_KERNEL);
-		if (!new_xattr->name) {
-			kfree(new_xattr);
-			return -ENOMEM;
-		}
-	}
-
-	spin_lock(&info->lock);
-	list_for_each_entry(xattr, &info->xattr_list, list) {
-		if (!strcmp(name, xattr->name)) {
-			if (flags & XATTR_CREATE) {
-				xattr = new_xattr;
-				err = -EEXIST;
-			} else if (new_xattr) {
-				list_replace(&xattr->list, &new_xattr->list);
-			} else {
-				list_del(&xattr->list);
-			}
-			goto out;
-		}
-	}
-	if (flags & XATTR_REPLACE) {
-		xattr = new_xattr;
-		err = -ENODATA;
-	} else {
-		list_add(&new_xattr->list, &info->xattr_list);
-		xattr = NULL;
-	}
-out:
-	spin_unlock(&info->lock);
-	if (xattr)
-		kfree(xattr->name);
-	kfree(xattr);
-	return err;
-}
-
 static const struct xattr_handler *shmem_xattr_handlers[] = {
 #ifdef CONFIG_TMPFS_POSIX_ACL
 	&generic_acl_access_handler,
@@ -2226,6 +2114,7 @@ static int shmem_xattr_validate(const char *name)
 static ssize_t shmem_getxattr(struct dentry *dentry, const char *name,
 			      void *buffer, size_t size)
 {
+	struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
 	int err;
 
 	/*
@@ -2240,12 +2129,13 @@ static ssize_t shmem_getxattr(struct dentry *dentry, const char *name,
 	if (err)
 		return err;
 
-	return shmem_xattr_get(dentry, name, buffer, size);
+	return simple_xattr_get(&info->xattrs, name, buffer, size);
 }
 
 static int shmem_setxattr(struct dentry *dentry, const char *name,
 			  const void *value, size_t size, int flags)
 {
+	struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
 	int err;
 
 	/*
@@ -2260,15 +2150,12 @@ static int shmem_setxattr(struct dentry *dentry, const char *name,
 	if (err)
 		return err;
 
-	if (size == 0)
-		value = "";  /* empty EA, do not remove */
-
-	return shmem_xattr_set(dentry->d_inode, name, value, size, flags);
-
+	return simple_xattr_set(&info->xattrs, name, value, size, flags);
 }
 
 static int shmem_removexattr(struct dentry *dentry, const char *name)
 {
+	struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
 	int err;
 
 	/*
@@ -2283,45 +2170,13 @@ static int shmem_removexattr(struct dentry *dentry, const char *name)
 	if (err)
 		return err;
 
-	return shmem_xattr_set(dentry->d_inode, name, NULL, 0, XATTR_REPLACE);
-}
-
-static bool xattr_is_trusted(const char *name)
-{
-	return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
+	return simple_xattr_remove(&info->xattrs, name);
 }
 
 static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
 {
-	bool trusted = capable(CAP_SYS_ADMIN);
-	struct shmem_xattr *xattr;
-	struct shmem_inode_info *info;
-	size_t used = 0;
-
-	info = SHMEM_I(dentry->d_inode);
-
-	spin_lock(&info->lock);
-	list_for_each_entry(xattr, &info->xattr_list, list) {
-		size_t len;
-
-		/* skip "trusted." attributes for unprivileged callers */
-		if (!trusted && xattr_is_trusted(xattr->name))
-			continue;
-
-		len = strlen(xattr->name) + 1;
-		used += len;
-		if (buffer) {
-			if (size < used) {
-				used = -ERANGE;
-				break;
-			}
-			memcpy(buffer, xattr->name, len);
-			buffer += len;
-		}
-	}
-	spin_unlock(&info->lock);
-
-	return used;
+	struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
+	return simple_xattr_list(&info->xattrs, buffer, size);
 }
 #endif /* CONFIG_TMPFS_XATTR */
 

net/core/netprio_cgroup.c

@@ -326,9 +326,7 @@ struct cgroup_subsys net_prio_subsys = {
 	.create		= cgrp_create,
 	.destroy	= cgrp_destroy,
 	.attach		= net_prio_attach,
-#ifdef CONFIG_NETPRIO_CGROUP
 	.subsys_id	= net_prio_subsys_id,
-#endif
 	.base_cftypes	= ss_files,
 	.module		= THIS_MODULE
 };
@@ -366,10 +364,6 @@ static int __init init_cgroup_netprio(void)
 	ret = cgroup_load_subsys(&net_prio_subsys);
 	if (ret)
 		goto out;
-#ifndef CONFIG_NETPRIO_CGROUP
-	smp_wmb();
-	net_prio_subsys_id = net_prio_subsys.subsys_id;
-#endif
 
 	register_netdevice_notifier(&netprio_device_notifier);
 
@@ -386,11 +380,6 @@ static void __exit exit_cgroup_netprio(void)
 
 	cgroup_unload_subsys(&net_prio_subsys);
 
-#ifndef CONFIG_NETPRIO_CGROUP
-	net_prio_subsys_id = -1;
-	synchronize_rcu();
-#endif
-
 	rtnl_lock();
 	for_each_netdev(&init_net, dev) {
 		old = rtnl_dereference(dev->priomap);

net/core/sock.c

@@ -326,17 +326,6 @@ int __sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 }
 EXPORT_SYMBOL(__sk_backlog_rcv);
 
-#if defined(CONFIG_CGROUPS)
-#if !defined(CONFIG_NET_CLS_CGROUP)
-int net_cls_subsys_id = -1;
-EXPORT_SYMBOL_GPL(net_cls_subsys_id);
-#endif
-#if !defined(CONFIG_NETPRIO_CGROUP)
-int net_prio_subsys_id = -1;
-EXPORT_SYMBOL_GPL(net_prio_subsys_id);
-#endif
-#endif
-
 static int sock_set_timeout(long *timeo_p, char __user *optval, int optlen)
 {
 	struct timeval tv;
@@ -1224,6 +1213,7 @@ static void sk_prot_free(struct proto *prot, struct sock *sk)
 }
 
 #ifdef CONFIG_CGROUPS
+#if IS_ENABLED(CONFIG_NET_CLS_CGROUP)
 void sock_update_classid(struct sock *sk)
 {
 	u32 classid;
@@ -1235,7 +1225,9 @@ void sock_update_classid(struct sock *sk)
 		sk->sk_classid = classid;
 }
 EXPORT_SYMBOL(sock_update_classid);
+#endif
 
+#if IS_ENABLED(CONFIG_NETPRIO_CGROUP)
 void sock_update_netprioidx(struct sock *sk, struct task_struct *task)
 {
 	if (in_interrupt())
@@ -1245,6 +1237,7 @@ void sock_update_netprioidx(struct sock *sk, struct task_struct *task)
 }
 EXPORT_SYMBOL_GPL(sock_update_netprioidx);
 #endif
+#endif
 
 /**
  *	sk_alloc - All socket objects are allocated here

net/sched/cls_cgroup.c

@@ -77,9 +77,7 @@ struct cgroup_subsys net_cls_subsys = {
 	.name		= "net_cls",
 	.create		= cgrp_create,
 	.destroy	= cgrp_destroy,
-#ifdef CONFIG_NET_CLS_CGROUP
 	.subsys_id	= net_cls_subsys_id,
-#endif
 	.base_cftypes	= ss_files,
 	.module		= THIS_MODULE,
 };
@@ -283,12 +281,6 @@ static int __init init_cgroup_cls(void)
 	if (ret)
 		goto out;
 
-#ifndef CONFIG_NET_CLS_CGROUP
-	/* We can't use rcu_assign_pointer because this is an int. */
-	smp_wmb();
-	net_cls_subsys_id = net_cls_subsys.subsys_id;
-#endif
-
 	ret = register_tcf_proto_ops(&cls_cgroup_ops);
 	if (ret)
 		cgroup_unload_subsys(&net_cls_subsys);
@@ -301,11 +293,6 @@ static void __exit exit_cgroup_cls(void)
 {
 	unregister_tcf_proto_ops(&cls_cgroup_ops);
 
-#ifndef CONFIG_NET_CLS_CGROUP
-	net_cls_subsys_id = -1;
-	synchronize_rcu();
-#endif
-
 	cgroup_unload_subsys(&net_cls_subsys);
 }