Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (52 commits)
  sched: fix RCU lockdep splat from task_group()
  rcu: using ACCESS_ONCE() to observe the jiffies_stall/rnp->qsmask value
  sched: suppress RCU lockdep splat in task_fork_fair
  net: suppress RCU lockdep false positive in sock_update_classid
  rcu: move check from rcu_dereference_bh to rcu_read_lock_bh_held
  rcu: Add advice to PROVE_RCU_REPEATEDLY kernel config parameter
  rcu: Add tracing data to support queueing models
  rcu: fix sparse errors in rcutorture.c
  rcu: only one evaluation of arg in rcu_dereference_check() unless sparse
  kernel: Remove undead ifdef CONFIG_DEBUG_LOCK_ALLOC
  rcu: fix _oddness handling of verbose stall warnings
  rcu: performance fixes to TINY_PREEMPT_RCU callback checking
  rcu: upgrade stallwarn.txt documentation for CPU-bound RT processes
  vhost: add __rcu annotations
  rcu: add comment stating that list_empty() applies to RCU-protected lists
  rcu: apply TINY_PREEMPT_RCU read-side speedup to TREE_PREEMPT_RCU
  rcu: combine duplicate code, courtesy of CONFIG_PREEMPT_RCU
  rcu: Upgrade srcu_read_lock() docbook about SRCU grace periods
  rcu: document ways of stalling updates in low-memory situations
  rcu: repair code-duplication FIXMEs
  ...

27 files changed, 527 insertions, 332 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 0c991023ee4..709dfb901d1 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -75,7 +75,7 @@ struct cgroup_subsys_state {
 
         unsigned long flags;
         /* ID for this css, if possible */
-        struct css_id *id;
+        struct css_id __rcu *id;
 };
 
 /* bits in struct cgroup_subsys_state flags field */
@@ -205,7 +205,7 @@ struct cgroup {
         struct list_head children;      /* my children */
 
         struct cgroup *parent;          /* my parent */
-        struct dentry *dentry;          /* cgroup fs entry, RCU protected */
+        struct dentry __rcu *dentry;    /* cgroup fs entry, RCU protected */
 
         /* Private pointers for each registered subsystem */
         struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index c1a62c56a66..320d6c94ff8 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -16,7 +16,11 @@
 # define __release(x)   __context__(x,-1)
 # define __cond_lock(x,c)       ((c) ? ({ __acquire(x); 1; }) : 0)
 # define __percpu       __attribute__((noderef, address_space(3)))
+#ifdef CONFIG_SPARSE_RCU_POINTER
+# define __rcu          __attribute__((noderef, address_space(4)))
+#else
 # define __rcu
+#endif
 extern void __chk_user_ptr(const volatile void __user *);
 extern void __chk_io_ptr(const volatile void __iomem *);
 #else
diff --git a/include/linux/cred.h b/include/linux/cred.h
index 4d2c39573f3..4aaeab37644 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -84,7 +84,7 @@ struct thread_group_cred {
         atomic_t        usage;
         pid_t           tgid;                   /* thread group process ID */
         spinlock_t      lock;
-        struct key      *session_keyring;       /* keyring inherited over fork */
+        struct key __rcu *session_keyring;      /* keyring inherited over fork */
         struct key      *process_keyring;       /* keyring private to this process */
         struct rcu_head rcu;                    /* RCU deletion hook */
 };
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index f59ed297b66..133c0ba25e3 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -31,7 +31,7 @@ struct embedded_fd_set {
 
 struct fdtable {
         unsigned int max_fds;
-        struct file ** fd;      /* current fd array */
+        struct file __rcu **fd;      /* current fd array */
         fd_set *close_on_exec;
         fd_set *open_fds;
         struct rcu_head rcu;
@@ -46,7 +46,7 @@ struct files_struct {
    * read mostly part
    */
         atomic_t count;
-        struct fdtable *fdt;
+        struct fdtable __rcu *fdt;
         struct fdtable fdtab;
   /*
    * written part on a separate cache line in SMP
@@ -55,7 +55,7 @@ struct files_struct {
         int next_fd;
         struct embedded_fd_set close_on_exec_init;
         struct embedded_fd_set open_fds_init;
-        struct file * fd_array[NR_OPEN_DEFAULT];
+        struct file __rcu * fd_array[NR_OPEN_DEFAULT];
 };
 
 #define rcu_dereference_check_fdtable(files, fdtfd) \
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 63d069bd80b..3168dcfb94f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1384,7 +1384,7 @@ struct super_block {
          * Saved mount options for lazy filesystems using
          * generic_show_options()
          */
-        char *s_options;
+        char __rcu *s_options;
 };
 
 extern struct timespec current_fs_time(struct super_block *sb);
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 5f2f4c4d8fb..af3f06b41dc 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -129,8 +129,8 @@ struct blk_scsi_cmd_filter {
 struct disk_part_tbl {
         struct rcu_head rcu_head;
         int len;
-        struct hd_struct *last_lookup;
-        struct hd_struct *part[];
+        struct hd_struct __rcu *last_lookup;
+        struct hd_struct __rcu *part[];
 };
 
 struct gendisk {
@@ -149,7 +149,7 @@ struct gendisk {
          * non-critical accesses use RCU.  Always access through
          * helpers.
          */
-        struct disk_part_tbl *part_tbl;
+        struct disk_part_tbl __rcu *part_tbl;
         struct hd_struct part0;
 
         const struct block_device_operations *fops;
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index d5b387669da..1f4517d55b1 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -139,7 +139,7 @@ static inline void account_system_vtime(struct task_struct *tsk)
 #endif
 
 #if defined(CONFIG_NO_HZ)
-#if defined(CONFIG_TINY_RCU)
+#if defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
 extern void rcu_enter_nohz(void);
 extern void rcu_exit_nohz(void);
 
diff --git a/include/linux/idr.h b/include/linux/idr.h
index e968db71e33..cdb715e58e3 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -50,14 +50,14 @@
 
 struct idr_layer {
         unsigned long            bitmap; /* A zero bit means "space here" */
-        struct idr_layer        *ary[1<<IDR_BITS];
+        struct idr_layer __rcu  *ary[1<<IDR_BITS];
         int                      count;  /* When zero, we can release it */
         int                      layer;  /* distance from leaf */
         struct rcu_head          rcu_head;
 };
 
 struct idr {
-        struct idr_layer *top;
+        struct idr_layer __rcu *top;
         struct idr_layer *id_free;
         int               layers; /* only valid without concurrent changes */
         int               id_free_cnt;
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 1f43fa56f60..2fea6c8ef6b 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -82,11 +82,17 @@ extern struct group_info init_groups;
 # define CAP_INIT_BSET  CAP_FULL_SET
 
 #ifdef CONFIG_TREE_PREEMPT_RCU
+#define INIT_TASK_RCU_TREE_PREEMPT()                                    \
+        .rcu_blocked_node = NULL,
+#else
+#define INIT_TASK_RCU_TREE_PREEMPT(tsk)
+#endif
+#ifdef CONFIG_PREEMPT_RCU
 #define INIT_TASK_RCU_PREEMPT(tsk)                                      \
         .rcu_read_lock_nesting = 0,                                     \
         .rcu_read_unlock_special = 0,                                   \
-        .rcu_blocked_node = NULL,                                       \
-        .rcu_node_entry = LIST_HEAD_INIT(tsk.rcu_node_entry),
+        .rcu_node_entry = LIST_HEAD_INIT(tsk.rcu_node_entry),           \
+        INIT_TASK_RCU_TREE_PREEMPT()
 #else
 #define INIT_TASK_RCU_PREEMPT(tsk)
 #endif
@@ -137,8 +143,8 @@ extern struct cred init_cred;
         .children       = LIST_HEAD_INIT(tsk.children),                 \
         .sibling        = LIST_HEAD_INIT(tsk.sibling),                  \
         .group_leader   = &tsk,                                         \
-        .real_cred      = &init_cred,                                   \
-        .cred           = &init_cred,                                   \
+        RCU_INIT_POINTER(.real_cred, &init_cred),                       \
+        RCU_INIT_POINTER(.cred, &init_cred),                            \
         .cred_guard_mutex =                                             \
                  __MUTEX_INITIALIZER(tsk.cred_guard_mutex),             \
         .comm           = "swapper",                                    \
diff --git a/include/linux/input.h b/include/linux/input.h
index 896a92227bc..d6ae1761be9 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -1196,7 +1196,7 @@ struct input_dev {
         int (*flush)(struct input_dev *dev, struct file *file);
         int (*event)(struct input_dev *dev, unsigned int type, unsigned int code, int value);
 
-        struct input_handle *grab;
+        struct input_handle __rcu *grab;
 
         spinlock_t event_lock;
         struct mutex mutex;
diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h
index 64d52913303..3e70b21884a 100644
--- a/include/linux/iocontext.h
+++ b/include/linux/iocontext.h
@@ -53,7 +53,7 @@ struct io_context {
 
         struct radix_tree_root radix_root;
         struct hlist_head cic_list;
-        void *ioc_data;
+        void __rcu *ioc_data;
 };
 
 static inline struct io_context *ioc_task_link(struct io_context *ioc)
diff --git a/include/linux/key.h b/include/linux/key.h
index cd50dfa1d4c..3db0adce1fd 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -178,8 +178,9 @@ struct key {
          */
         union {
                 unsigned long           value;
+                void __rcu              *rcudata;
                 void                    *data;
-                struct keyring_list     *subscriptions;
+                struct keyring_list __rcu *subscriptions;
         } payload;
 };
 
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c13cc48697a..ac740b26eb1 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -205,7 +205,7 @@ struct kvm {
 
         struct mutex irq_lock;
 #ifdef CONFIG_HAVE_KVM_IRQCHIP
-        struct kvm_irq_routing_table *irq_routing;
+        struct kvm_irq_routing_table __rcu *irq_routing;
         struct hlist_head mask_notifier_list;
         struct hlist_head irq_ack_notifier_list;
 #endif
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index ee7e258627f..cb57d657ce4 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -299,7 +299,7 @@ struct mm_struct {
          * new_owner->mm == mm
          * new_owner->alloc_lock is held
          */
-        struct task_struct *owner;
+        struct task_struct __rcu *owner;
 #endif
 
 #ifdef CONFIG_PROC_FS
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 508f8cf6da3..d0edf7d823a 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -185,7 +185,7 @@ struct nfs_inode {
         struct nfs4_cached_acl  *nfs4_acl;
         /* NFSv4 state */
         struct list_head        open_states;
-        struct nfs_delegation   *delegation;
+        struct nfs_delegation __rcu *delegation;
         fmode_t                  delegation_state;
         struct rw_semaphore     rwsem;
 #endif /* CONFIG_NFS_V4*/
diff --git a/include/linux/notifier.h b/include/linux/notifier.h
index b2f1a4d8355..2026f9e1ceb 100644
--- a/include/linux/notifier.h
+++ b/include/linux/notifier.h
@@ -49,28 +49,28 @@
 
 struct notifier_block {
         int (*notifier_call)(struct notifier_block *, unsigned long, void *);
-        struct notifier_block *next;
+        struct notifier_block __rcu *next;
         int priority;
 };
 
 struct atomic_notifier_head {
         spinlock_t lock;
-        struct notifier_block *head;
+        struct notifier_block __rcu *head;
 };
 
 struct blocking_notifier_head {
         struct rw_semaphore rwsem;
-        struct notifier_block *head;
+        struct notifier_block __rcu *head;
 };
 
 struct raw_notifier_head {
-        struct notifier_block *head;
+        struct notifier_block __rcu *head;
 };
 
 struct srcu_notifier_head {
         struct mutex mutex;
         struct srcu_struct srcu;
-        struct notifier_block *head;
+        struct notifier_block __rcu *head;
 };
 
 #define ATOMIC_INIT_NOTIFIER_HEAD(name) do {    \
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 634b8e674ac..a39cbed9ee1 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -47,6 +47,8 @@ static inline void *radix_tree_indirect_to_ptr(void *ptr)
 {
         return (void *)((unsigned long)ptr & ~RADIX_TREE_INDIRECT_PTR);
 }
+#define radix_tree_indirect_to_ptr(ptr) \
+        radix_tree_indirect_to_ptr((void __force *)(ptr))
 
 static inline int radix_tree_is_indirect_ptr(void *ptr)
 {
@@ -61,7 +63,7 @@ static inline int radix_tree_is_indirect_ptr(void *ptr)
 struct radix_tree_root {
         unsigned int            height;
         gfp_t                   gfp_mask;
-        struct radix_tree_node  *rnode;
+        struct radix_tree_node  __rcu *rnode;
 };
 
 #define RADIX_TREE_INIT(mask)   {                                       \
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 4ec3b38ce9c..f31ef61f1c6 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -10,6 +10,21 @@
 #include <linux/rcupdate.h>
 
 /*
+ * Why is there no list_empty_rcu()?  Because list_empty() serves this
+ * purpose.  The list_empty() function fetches the RCU-protected pointer
+ * and compares it to the address of the list head, but neither dereferences
+ * this pointer itself nor provides this pointer to the caller.  Therefore,
+ * it is not necessary to use rcu_dereference(), so that list_empty() can
+ * be used anywhere you would want to use a list_empty_rcu().
+ */
+
+/*
+ * return the ->next pointer of a list_head in an rcu safe
+ * way, we must not access it directly
+ */
+#define list_next_rcu(list)     (*((struct list_head __rcu **)(&(list)->next)))
+
+/*
  * Insert a new entry between two known consecutive entries.
  *
  * This is only for internal list manipulation where we know
@@ -20,7 +35,7 @@ static inline void __list_add_rcu(struct list_head *new,
 {
         new->next = next;
         new->prev = prev;
-        rcu_assign_pointer(prev->next, new);
+        rcu_assign_pointer(list_next_rcu(prev), new);
         next->prev = new;
 }
 
@@ -138,7 +153,7 @@ static inline void list_replace_rcu(struct list_head *old,
 {
         new->next = old->next;
         new->prev = old->prev;
-        rcu_assign_pointer(new->prev->next, new);
+        rcu_assign_pointer(list_next_rcu(new->prev), new);
         new->next->prev = new;
         old->prev = LIST_POISON2;
 }
@@ -193,7 +208,7 @@ static inline void list_splice_init_rcu(struct list_head *list,
          */
 
         last->next = at;
-        rcu_assign_pointer(head->next, first);
+        rcu_assign_pointer(list_next_rcu(head), first);
         first->prev = head;
         at->prev = last;
 }
@@ -208,7 +223,9 @@ static inline void list_splice_init_rcu(struct list_head *list,
  * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
  */
 #define list_entry_rcu(ptr, type, member) \
-        container_of(rcu_dereference_raw(ptr), type, member)
+        ({typeof (*ptr) __rcu *__ptr = (typeof (*ptr) __rcu __force *)ptr; \
+         container_of((typeof(ptr))rcu_dereference_raw(__ptr), type, member); \
+        })
 
 /**
  * list_first_entry_rcu - get the first element from a list
@@ -225,9 +242,9 @@ static inline void list_splice_init_rcu(struct list_head *list,
         list_entry_rcu((ptr)->next, type, member)
 
 #define __list_for_each_rcu(pos, head) \
-        for (pos = rcu_dereference_raw((head)->next); \
+        for (pos = rcu_dereference_raw(list_next_rcu(head)); \
                 pos != (head); \
-                pos = rcu_dereference_raw(pos->next))
+                pos = rcu_dereference_raw(list_next_rcu((pos)))
 
 /**
  * list_for_each_entry_rcu      -       iterate over rcu list of given type
@@ -257,9 +274,9 @@ static inline void list_splice_init_rcu(struct list_head *list,
  * as long as the traversal is guarded by rcu_read_lock().
  */
 #define list_for_each_continue_rcu(pos, head) \
-        for ((pos) = rcu_dereference_raw((pos)->next); \
+        for ((pos) = rcu_dereference_raw(list_next_rcu(pos)); \
                 prefetch((pos)->next), (pos) != (head); \
-                (pos) = rcu_dereference_raw((pos)->next))
+                (pos) = rcu_dereference_raw(list_next_rcu(pos)))
 
 /**
  * list_for_each_entry_continue_rcu - continue iteration over list of given type
@@ -314,12 +331,19 @@ static inline void hlist_replace_rcu(struct hlist_node *old,
 
         new->next = next;
         new->pprev = old->pprev;
-        rcu_assign_pointer(*new->pprev, new);
+        rcu_assign_pointer(*(struct hlist_node __rcu **)new->pprev, new);
         if (next)
                 new->next->pprev = &new->next;
         old->pprev = LIST_POISON2;
 }
 
+/*
+ * return the first or the next element in an RCU protected hlist
+ */
+#define hlist_first_rcu(head)   (*((struct hlist_node __rcu **)(&(head)->first)))
+#define hlist_next_rcu(node)    (*((struct hlist_node __rcu **)(&(node)->next)))
+#define hlist_pprev_rcu(node)   (*((struct hlist_node __rcu **)((node)->pprev)))
+
 /**
  * hlist_add_head_rcu
  * @n: the element to add to the hash list.
@@ -346,7 +370,7 @@ static inline void hlist_add_head_rcu(struct hlist_node *n,
 
         n->next = first;
         n->pprev = &h->first;
-        rcu_assign_pointer(h->first, n);
+        rcu_assign_pointer(hlist_first_rcu(h), n);
         if (first)
                 first->pprev = &n->next;
 }
@@ -374,7 +398,7 @@ static inline void hlist_add_before_rcu(struct hlist_node *n,
 {
         n->pprev = next->pprev;
         n->next = next;
-        rcu_assign_pointer(*(n->pprev), n);
+        rcu_assign_pointer(hlist_pprev_rcu(n), n);
         next->pprev = &n->next;
 }
 
@@ -401,15 +425,15 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev,
 {
         n->next = prev->next;
         n->pprev = &prev->next;
-        rcu_assign_pointer(prev->next, n);
+        rcu_assign_pointer(hlist_next_rcu(prev), n);
         if (n->next)
                 n->next->pprev = &n->next;
 }
 
-#define __hlist_for_each_rcu(pos, head)                 \
-        for (pos = rcu_dereference((head)->first);      \
-             pos && ({ prefetch(pos->next); 1; });      \
-             pos = rcu_dereference(pos->next))
+#define __hlist_for_each_rcu(pos, head)                         \
+        for (pos = rcu_dereference(hlist_first_rcu(head));      \
+             pos && ({ prefetch(pos->next); 1; });              \
+             pos = rcu_dereference(hlist_next_rcu(pos)))
 
 /**
  * hlist_for_each_entry_rcu - iterate over rcu list of given type
@@ -422,11 +446,11 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev,
  * the _rcu list-mutation primitives such as hlist_add_head_rcu()
  * as long as the traversal is guarded by rcu_read_lock().
  */
-#define hlist_for_each_entry_rcu(tpos, pos, head, member)                \
-        for (pos = rcu_dereference_raw((head)->first);                   \
+#define hlist_for_each_entry_rcu(tpos, pos, head, member)               \
+        for (pos = rcu_dereference_raw(hlist_first_rcu(head));          \
                 pos && ({ prefetch(pos->next); 1; }) &&                  \
                 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
-                pos = rcu_dereference_raw(pos->next))
+                pos = rcu_dereference_raw(hlist_next_rcu(pos)))
 
 /**
  * hlist_for_each_entry_rcu_bh - iterate over rcu list of given type
diff --git a/include/linux/rculist_nulls.h b/include/linux/rculist_nulls.h
index b70ffe53cb9..2ae13714828 100644
--- a/include/linux/rculist_nulls.h
+++ b/include/linux/rculist_nulls.h
@@ -37,6 +37,12 @@ static inline void hlist_nulls_del_init_rcu(struct hlist_nulls_node *n)
         }
 }
 
+#define hlist_nulls_first_rcu(head) \
+        (*((struct hlist_nulls_node __rcu __force **)&(head)->first))
+
+#define hlist_nulls_next_rcu(node) \
+        (*((struct hlist_nulls_node __rcu __force **)&(node)->next))
+
 /**
  * hlist_nulls_del_rcu - deletes entry from hash list without re-initialization
  * @n: the element to delete from the hash list.
@@ -88,7 +94,7 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n,
 
         n->next = first;
         n->pprev = &h->first;
-        rcu_assign_pointer(h->first, n);
+        rcu_assign_pointer(hlist_nulls_first_rcu(h), n);
         if (!is_a_nulls(first))
                 first->pprev = &n->next;
 }
@@ -100,11 +106,11 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n,
  * @member:     the name of the hlist_nulls_node within the struct.
  *
  */
-#define hlist_nulls_for_each_entry_rcu(tpos, pos, head, member) \
-        for (pos = rcu_dereference_raw((head)->first);                   \
-                (!is_a_nulls(pos)) &&                   \
+#define hlist_nulls_for_each_entry_rcu(tpos, pos, head, member)                 \
+        for (pos = rcu_dereference_raw(hlist_nulls_first_rcu(head));            \
+                (!is_a_nulls(pos)) &&                                           \
                 ({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); 1; }); \
-                pos = rcu_dereference_raw(pos->next))
+                pos = rcu_dereference_raw(hlist_nulls_next_rcu(pos)))
 
 #endif
 #endif
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 83af1f8d8b7..03cda7bed98 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -41,11 +41,15 @@
 #include <linux/lockdep.h>
 #include <linux/completion.h>
 #include <linux/debugobjects.h>
+#include <linux/compiler.h>
 
 #ifdef CONFIG_RCU_TORTURE_TEST
 extern int rcutorture_runnable; /* for sysctl */
 #endif /* #ifdef CONFIG_RCU_TORTURE_TEST */
 
+#define ULONG_CMP_GE(a, b)      (ULONG_MAX / 2 >= (a) - (b))
+#define ULONG_CMP_LT(a, b)      (ULONG_MAX / 2 < (a) - (b))
+
 /**
  * struct rcu_head - callback structure for use with RCU
  * @next: next update requests in a list
@@ -57,29 +61,94 @@ struct rcu_head {
 };
 
 /* Exported common interfaces */
-extern void rcu_barrier(void);
+extern void call_rcu_sched(struct rcu_head *head,
+                           void (*func)(struct rcu_head *rcu));
+extern void synchronize_sched(void);
 extern void rcu_barrier_bh(void);
 extern void rcu_barrier_sched(void);
 extern void synchronize_sched_expedited(void);
 extern int sched_expedited_torture_stats(char *page);
 
+static inline void __rcu_read_lock_bh(void)
+{
+        local_bh_disable();
+}
+
+static inline void __rcu_read_unlock_bh(void)
+{
+        local_bh_enable();
+}
+
+#ifdef CONFIG_PREEMPT_RCU
+
+extern void __rcu_read_lock(void);
+extern void __rcu_read_unlock(void);
+void synchronize_rcu(void);
+
+/*
+ * Defined as a macro as it is a very low level header included from
+ * areas that don't even know about current.  This gives the rcu_read_lock()
+ * nesting depth, but makes sense only if CONFIG_PREEMPT_RCU -- in other
+ * types of kernel builds, the rcu_read_lock() nesting depth is unknowable.
+ */
+#define rcu_preempt_depth() (current->rcu_read_lock_nesting)
+
+#else /* #ifdef CONFIG_PREEMPT_RCU */
+
+static inline void __rcu_read_lock(void)
+{
+        preempt_disable();
+}
+
+static inline void __rcu_read_unlock(void)
+{
+        preempt_enable();
+}
+
+static inline void synchronize_rcu(void)
+{
+        synchronize_sched();
+}
+
+static inline int rcu_preempt_depth(void)
+{
+        return 0;
+}
+
+#endif /* #else #ifdef CONFIG_PREEMPT_RCU */
+
 /* Internal to kernel */
 extern void rcu_init(void);
+extern void rcu_sched_qs(int cpu);
+extern void rcu_bh_qs(int cpu);
+extern void rcu_check_callbacks(int cpu, int user);
+struct notifier_block;
+
+#ifdef CONFIG_NO_HZ
+
+extern void rcu_enter_nohz(void);
+extern void rcu_exit_nohz(void);
+
+#else /* #ifdef CONFIG_NO_HZ */
+
+static inline void rcu_enter_nohz(void)
+{
+}
+
+static inline void rcu_exit_nohz(void)
+{
+}
+
+#endif /* #else #ifdef CONFIG_NO_HZ */
 
 #if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
 #include <linux/rcutree.h>
-#elif defined(CONFIG_TINY_RCU)
+#elif defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
 #include <linux/rcutiny.h>
 #else
 #error "Unknown RCU implementation specified to kernel configuration"
 #endif
 
-#define RCU_HEAD_INIT   { .next = NULL, .func = NULL }
-#define RCU_HEAD(head) struct rcu_head head = RCU_HEAD_INIT
-#define INIT_RCU_HEAD(ptr) do { \
-       (ptr)->next = NULL; (ptr)->func = NULL; \
-} while (0)
-
 /*
  * init_rcu_head_on_stack()/destroy_rcu_head_on_stack() are needed for dynamic
  * initialization and destruction of rcu_head on the stack. rcu_head structures
@@ -120,14 +189,15 @@ extern struct lockdep_map rcu_sched_lock_map;
 extern int debug_lockdep_rcu_enabled(void);
 
 /**
- * rcu_read_lock_held - might we be in RCU read-side critical section?
+ * rcu_read_lock_held() - might we be in RCU read-side critical section?
  *
  * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an RCU
  * read-side critical section.  In absence of CONFIG_DEBUG_LOCK_ALLOC,
  * this assumes we are in an RCU read-side critical section unless it can
- * prove otherwise.
+ * prove otherwise.  This is useful for debug checks in functions that
+ * require that they be called within an RCU read-side critical section.
  *
- * Check debug_lockdep_rcu_enabled() to prevent false positives during boot
+ * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot
  * and while lockdep is disabled.
  */
 static inline int rcu_read_lock_held(void)
@@ -144,14 +214,16 @@ static inline int rcu_read_lock_held(void)
 extern int rcu_read_lock_bh_held(void);
 
 /**
- * rcu_read_lock_sched_held - might we be in RCU-sched read-side critical section?
+ * rcu_read_lock_sched_held() - might we be in RCU-sched read-side critical section?
  *
  * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an
  * RCU-sched read-side critical section.  In absence of
  * CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side
  * critical section unless it can prove otherwise.  Note that disabling
  * of preemption (including disabling irqs) counts as an RCU-sched
- * read-side critical section.
+ * read-side critical section.  This is useful for debug checks in functions
+ * that required that they be called within an RCU-sched read-side
+ * critical section.
  *
  * Check debug_lockdep_rcu_enabled() to prevent false positives during boot
  * and while lockdep is disabled.
@@ -211,7 +283,11 @@ static inline int rcu_read_lock_sched_held(void)
 
 extern int rcu_my_thread_group_empty(void);
 
-#define __do_rcu_dereference_check(c)                                   \
+/**
+ * rcu_lockdep_assert - emit lockdep splat if specified condition not met
+ * @c: condition to check
+ */
+#define rcu_lockdep_assert(c)                                           \
         do {                                                            \
                 static bool __warned;                                   \
                 if (debug_lockdep_rcu_enabled() && !__warned && !(c)) { \
@@ -220,41 +296,163 @@ extern int rcu_my_thread_group_empty(void);
                 }                                                       \
         } while (0)
 
+#else /* #ifdef CONFIG_PROVE_RCU */
+
+#define rcu_lockdep_assert(c) do { } while (0)
+
+#endif /* #else #ifdef CONFIG_PROVE_RCU */
+
+/*
+ * Helper functions for rcu_dereference_check(), rcu_dereference_protected()
+ * and rcu_assign_pointer().  Some of these could be folded into their
+ * callers, but they are left separate in order to ease introduction of
+ * multiple flavors of pointers to match the multiple flavors of RCU
+ * (e.g., __rcu_bh, * __rcu_sched, and __srcu), should this make sense in
+ * the future.
+ */
+
+#ifdef __CHECKER__
+#define rcu_dereference_sparse(p, space) \
+        ((void)(((typeof(*p) space *)p) == p))
+#else /* #ifdef __CHECKER__ */
+#define rcu_dereference_sparse(p, space)
+#endif /* #else #ifdef __CHECKER__ */
+
+#define __rcu_access_pointer(p, space) \
+        ({ \
+                typeof(*p) *_________p1 = (typeof(*p)*__force )ACCESS_ONCE(p); \
+                rcu_dereference_sparse(p, space); \
+                ((typeof(*p) __force __kernel *)(_________p1)); \
+        })
+#define __rcu_dereference_check(p, c, space) \
+        ({ \
+                typeof(*p) *_________p1 = (typeof(*p)*__force )ACCESS_ONCE(p); \
+                rcu_lockdep_assert(c); \
+                rcu_dereference_sparse(p, space); \
+                smp_read_barrier_depends(); \
+                ((typeof(*p) __force __kernel *)(_________p1)); \
+        })
+#define __rcu_dereference_protected(p, c, space) \
+        ({ \
+                rcu_lockdep_assert(c); \
+                rcu_dereference_sparse(p, space); \
+                ((typeof(*p) __force __kernel *)(p)); \
+        })
+
+#define __rcu_dereference_index_check(p, c) \
+        ({ \
+                typeof(p) _________p1 = ACCESS_ONCE(p); \
+                rcu_lockdep_assert(c); \
+                smp_read_barrier_depends(); \
+                (_________p1); \
+        })
+#define __rcu_assign_pointer(p, v, space) \
+        ({ \
+                if (!__builtin_constant_p(v) || \
+                    ((v) != NULL)) \
+                        smp_wmb(); \
+                (p) = (typeof(*v) __force space *)(v); \
+        })
+
+
+/**
+ * rcu_access_pointer() - fetch RCU pointer with no dereferencing
+ * @p: The pointer to read
+ *
+ * Return the value of the specified RCU-protected pointer, but omit the
+ * smp_read_barrier_depends() and keep the ACCESS_ONCE().  This is useful
+ * when the value of this pointer is accessed, but the pointer is not
+ * dereferenced, for example, when testing an RCU-protected pointer against
+ * NULL.  Although rcu_access_pointer() may also be used in cases where
+ * update-side locks prevent the value of the pointer from changing, you
+ * should instead use rcu_dereference_protected() for this use case.
+ */
+#define rcu_access_pointer(p) __rcu_access_pointer((p), __rcu)
+
 /**
- * rcu_dereference_check - rcu_dereference with debug checking
+ * rcu_dereference_check() - rcu_dereference with debug checking
  * @p: The pointer to read, prior to dereferencing
  * @c: The conditions under which the dereference will take place
  *
  * Do an rcu_dereference(), but check that the conditions under which the
- * dereference will take place are correct.  Typically the conditions indicate
- * the various locking conditions that should be held at that point.  The check
- * should return true if the conditions are satisfied.
+ * dereference will take place are correct.  Typically the conditions
+ * indicate the various locking conditions that should be held at that
+ * point.  The check should return true if the conditions are satisfied.
+ * An implicit check for being in an RCU read-side critical section
+ * (rcu_read_lock()) is included.
  *
  * For example:
  *
- *      bar = rcu_dereference_check(foo->bar, rcu_read_lock_held() ||
- *                                            lockdep_is_held(&foo->lock));
+ *      bar = rcu_dereference_check(foo->bar, lockdep_is_held(&foo->lock));
  *
  * could be used to indicate to lockdep that foo->bar may only be dereferenced
- * if either the RCU read lock is held, or that the lock required to replace
+ * if either rcu_read_lock() is held, or that the lock required to replace
  * the bar struct at foo->bar is held.
  *
  * Note that the list of conditions may also include indications of when a lock
  * need not be held, for example during initialisation or destruction of the
  * target struct:
  *
- *      bar = rcu_dereference_check(foo->bar, rcu_read_lock_held() ||
- *                                            lockdep_is_held(&foo->lock) ||
+ *      bar = rcu_dereference_check(foo->bar, lockdep_is_held(&foo->lock) ||
  *                                            atomic_read(&foo->usage) == 0);
+ *
+ * Inserts memory barriers on architectures that require them
+ * (currently only the Alpha), prevents the compiler from refetching
+ * (and from merging fetches), and, more importantly, documents exactly
+ * which pointers are protected by RCU and checks that the pointer is
+ * annotated as __rcu.
  */
 #define rcu_dereference_check(p, c) \
-        ({ \
-                __do_rcu_dereference_check(c); \
-                rcu_dereference_raw(p); \
-        })
+        __rcu_dereference_check((p), rcu_read_lock_held() || (c), __rcu)
+
+/**
+ * rcu_dereference_bh_check() - rcu_dereference_bh with debug checking
+ * @p: The pointer to read, prior to dereferencing
+ * @c: The conditions under which the dereference will take place
+ *
+ * This is the RCU-bh counterpart to rcu_dereference_check().
+ */
+#define rcu_dereference_bh_check(p, c) \
+        __rcu_dereference_check((p), rcu_read_lock_bh_held() || (c), __rcu)
 
 /**
- * rcu_dereference_protected - fetch RCU pointer when updates prevented
+ * rcu_dereference_sched_check() - rcu_dereference_sched with debug checking
+ * @p: The pointer to read, prior to dereferencing
+ * @c: The conditions under which the dereference will take place
+ *
+ * This is the RCU-sched counterpart to rcu_dereference_check().
+ */
+#define rcu_dereference_sched_check(p, c) \
+        __rcu_dereference_check((p), rcu_read_lock_sched_held() || (c), \
+                                __rcu)
+
+#define rcu_dereference_raw(p) rcu_dereference_check(p, 1) /*@@@ needed? @@@*/
+
+/**
+ * rcu_dereference_index_check() - rcu_dereference for indices with debug checking
+ * @p: The pointer to read, prior to dereferencing
+ * @c: The conditions under which the dereference will take place
+ *
+ * Similar to rcu_dereference_check(), but omits the sparse checking.
+ * This allows rcu_dereference_index_check() to be used on integers,
+ * which can then be used as array indices.  Attempting to use
+ * rcu_dereference_check() on an integer will give compiler warnings
+ * because the sparse address-space mechanism relies on dereferencing
+ * the RCU-protected pointer.  Dereferencing integers is not something
+ * that even gcc will put up with.
+ *
+ * Note that this function does not implicitly check for RCU read-side
+ * critical sections.  If this function gains lots of uses, it might
+ * make sense to provide versions for each flavor of RCU, but it does
+ * not make sense as of early 2010.
+ */
+#define rcu_dereference_index_check(p, c) \
+        __rcu_dereference_index_check((p), (c))
+
+/**
+ * rcu_dereference_protected() - fetch RCU pointer when updates prevented
+ * @p: The pointer to read, prior to dereferencing
+ * @c: The conditions under which the dereference will take place
  *
  * Return the value of the specified RCU-protected pointer, but omit
  * both the smp_read_barrier_depends() and the ACCESS_ONCE().  This
@@ -263,35 +461,61 @@ extern int rcu_my_thread_group_empty(void);
  * prevent the compiler from repeating this reference or combining it
  * with other references, so it should not be used without protection
  * of appropriate locks.
+ *
+ * This function is only for update-side use.  Using this function
+ * when protected only by rcu_read_lock() will result in infrequent
+ * but very ugly failures.
  */
 #define rcu_dereference_protected(p, c) \
-        ({ \
-                __do_rcu_dereference_check(c); \
-                (p); \
-        })
+        __rcu_dereference_protected((p), (c), __rcu)
 
-#else /* #ifdef CONFIG_PROVE_RCU */
+/**
+ * rcu_dereference_bh_protected() - fetch RCU-bh pointer when updates prevented
+ * @p: The pointer to read, prior to dereferencing
+ * @c: The conditions under which the dereference will take place
+ *
+ * This is the RCU-bh counterpart to rcu_dereference_protected().
+ */
+#define rcu_dereference_bh_protected(p, c) \
+        __rcu_dereference_protected((p), (c), __rcu)
 
-#define rcu_dereference_check(p, c)     rcu_dereference_raw(p)
-#define rcu_dereference_protected(p, c) (p)
+/**
+ * rcu_dereference_sched_protected() - fetch RCU-sched pointer when updates prevented
+ * @p: The pointer to read, prior to dereferencing
+ * @c: The conditions under which the dereference will take place
+ *
+ * This is the RCU-sched counterpart to rcu_dereference_protected().
+ */
+#define rcu_dereference_sched_protected(p, c) \
+        __rcu_dereference_protected((p), (c), __rcu)
 
-#endif /* #else #ifdef CONFIG_PROVE_RCU */
 
 /**
- * rcu_access_pointer - fetch RCU pointer with no dereferencing
+ * rcu_dereference() - fetch RCU-protected pointer for dereferencing
+ * @p: The pointer to read, prior to dereferencing
  *
- * Return the value of the specified RCU-protected pointer, but omit the
- * smp_read_barrier_depends() and keep the ACCESS_ONCE().  This is useful
- * when the value of this pointer is accessed, but the pointer is not
- * dereferenced, for example, when testing an RCU-protected pointer against
- * NULL.  This may also be used in cases where update-side locks prevent
- * the value of the pointer from changing, but rcu_dereference_protected()
- * is a lighter-weight primitive for this use case.
+ * This is a simple wrapper around rcu_dereference_check().
+ */
+#define rcu_dereference(p) rcu_dereference_check(p, 0)
+
+/**
+ * rcu_dereference_bh() - fetch an RCU-bh-protected pointer for dereferencing
+ * @p: The pointer to read, prior to dereferencing
+ *
+ * Makes rcu_dereference_check() do the dirty work.
+ */
+#define rcu_dereference_bh(p) rcu_dereference_bh_check(p, 0)
+
+/**
+ * rcu_dereference_sched() - fetch RCU-sched-protected pointer for dereferencing
+ * @p: The pointer to read, prior to dereferencing
+ *
+ * Makes rcu_dereference_check() do the dirty work.
  */
-#define rcu_access_pointer(p)   ACCESS_ONCE(p)
+#define rcu_dereference_sched(p) rcu_dereference_sched_check(p, 0)
 
 /**
- * rcu_read_lock - mark the beginning of an RCU read-side critical section.
+ * rcu_read_lock() - mark the beginning of an RCU read-side critical section
  *
  * When synchronize_rcu() is invoked on one CPU while other CPUs
  * are within RCU read-side critical sections, then the
@@ -302,7 +526,7 @@ extern int rcu_my_thread_group_empty(void);
  * until after the all the other CPUs exit their critical sections.
  *
  * Note, however, that RCU callbacks are permitted to run concurrently
- * with RCU read-side critical sections.  One way that this can happen
+ * with new RCU read-side critical sections.  One way that this can happen
  * is via the following sequence of events: (1) CPU 0 enters an RCU
  * read-side critical section, (2) CPU 1 invokes call_rcu() to register
  * an RCU callback, (3) CPU 0 exits the RCU read-side critical section,
@@ -317,7 +541,20 @@ extern int rcu_my_thread_group_empty(void);
  * will be deferred until the outermost RCU read-side critical section
  * completes.
  *
- * It is illegal to block while in an RCU read-side critical section.
+ * You can avoid reading and understanding the next paragraph by
+ * following this rule: don't put anything in an rcu_read_lock() RCU
+ * read-side critical section that would block in a !PREEMPT kernel.
+ * But if you want the full story, read on!
+ *
+ * In non-preemptible RCU implementations (TREE_RCU and TINY_RCU), it
+ * is illegal to block while in an RCU read-side critical section.  In
+ * preemptible RCU implementations (TREE_PREEMPT_RCU and TINY_PREEMPT_RCU)
+ * in CONFIG_PREEMPT kernel builds, RCU read-side critical sections may
+ * be preempted, but explicit blocking is illegal.  Finally, in preemptible
+ * RCU implementations in real-time (CONFIG_PREEMPT_RT) kernel builds,
+ * RCU read-side critical sections may be preempted and they may also
+ * block, but only when acquiring spinlocks that are subject to priority
+ * inheritance.
  */
 static inline void rcu_read_lock(void)
 {
@@ -337,7 +574,7 @@ static inline void rcu_read_lock(void)
  */
 
 /**
- * rcu_read_unlock - marks the end of an RCU read-side critical section.
+ * rcu_read_unlock() - marks the end of an RCU read-side critical section.
  *
  * See rcu_read_lock() for more information.
  */
@@ -349,15 +586,16 @@ static inline void rcu_read_unlock(void)
 }
 
 /**
- * rcu_read_lock_bh - mark the beginning of a softirq-only RCU critical section
+ * rcu_read_lock_bh() - mark the beginning of an RCU-bh critical section
  *
  * This is equivalent of rcu_read_lock(), but to be used when updates
- * are being done using call_rcu_bh(). Since call_rcu_bh() callbacks
- * consider completion of a softirq handler to be a quiescent state,
- * a process in RCU read-side critical section must be protected by
- * disabling softirqs. Read-side critical sections in interrupt context
- * can use just rcu_read_lock().
- *
+ * are being done using call_rcu_bh() or synchronize_rcu_bh(). Since
+ * both call_rcu_bh() and synchronize_rcu_bh() consider completion of a
+ * softirq handler to be a quiescent state, a process in RCU read-side
+ * critical section must be protected by disabling softirqs. Read-side
+ * critical sections in interrupt context can use just rcu_read_lock(),
+ * though this should at least be commented to avoid confusing people
+ * reading the code.
  */
 static inline void rcu_read_lock_bh(void)
 {
@@ -379,13 +617,12 @@ static inline void rcu_read_unlock_bh(void)
 }
 
 /**
- * rcu_read_lock_sched - mark the beginning of a RCU-classic critical section
+ * rcu_read_lock_sched() - mark the beginning of a RCU-sched critical section
  *
- * Should be used with either
- * - synchronize_sched()
- * or
- * - call_rcu_sched() and rcu_barrier_sched()
- * on the write-side to insure proper synchronization.
+ * This is equivalent of rcu_read_lock(), but to be used when updates
+ * are being done using call_rcu_sched() or synchronize_rcu_sched().
+ * Read-side critical sections can also be introduced by anything that
+ * disables preemption, including local_irq_disable() and friends.
  */
 static inline void rcu_read_lock_sched(void)
 {
@@ -420,54 +657,14 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
         preempt_enable_notrace();
 }
 
-
 /**
- * rcu_dereference_raw - fetch an RCU-protected pointer
+ * rcu_assign_pointer() - assign to RCU-protected pointer
+ * @p: pointer to assign to
+ * @v: value to assign (publish)
  *
- * The caller must be within some flavor of RCU read-side critical
- * section, or must be otherwise preventing the pointer from changing,
- * for example, by holding an appropriate lock.  This pointer may later
- * be safely dereferenced.  It is the caller's responsibility to have
- * done the right thing, as this primitive does no checking of any kind.
- *
- * Inserts memory barriers on architectures that require them
- * (currently only the Alpha), and, more importantly, documents
- * exactly which pointers are protected by RCU.
- */
-#define rcu_dereference_raw(p)  ({ \
-                                typeof(p) _________p1 = ACCESS_ONCE(p); \
-                                smp_read_barrier_depends(); \
-                                (_________p1); \
-                                })
-
-/**
- * rcu_dereference - fetch an RCU-protected pointer, checking for RCU
- *
- * Makes rcu_dereference_check() do the dirty work.
- */
-#define rcu_dereference(p) \
-        rcu_dereference_check(p, rcu_read_lock_held())
-
-/**
- * rcu_dereference_bh - fetch an RCU-protected pointer, checking for RCU-bh
- *
- * Makes rcu_dereference_check() do the dirty work.
- */
-#define rcu_dereference_bh(p) \
-                rcu_dereference_check(p, rcu_read_lock_bh_held() || irqs_disabled())
-
-/**
- * rcu_dereference_sched - fetch RCU-protected pointer, checking for RCU-sched
- *
- * Makes rcu_dereference_check() do the dirty work.
- */
-#define rcu_dereference_sched(p) \
-                rcu_dereference_check(p, rcu_read_lock_sched_held())
-
-/**
- * rcu_assign_pointer - assign (publicize) a pointer to a newly
- * initialized structure that will be dereferenced by RCU read-side
- * critical sections.  Returns the value assigned.
+ * Assigns the specified value to the specified RCU-protected
+ * pointer, ensuring that any concurrent RCU readers will see
+ * any prior initialization.  Returns the value assigned.
  *
  * Inserts memory barriers on architectures that require them
  * (pretty much all of them other than x86), and also prevents
@@ -476,14 +673,17 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
  * call documents which pointers will be dereferenced by RCU read-side
  * code.
  */
-
 #define rcu_assign_pointer(p, v) \
-        ({ \
-                if (!__builtin_constant_p(v) || \
-                    ((v) != NULL)) \
-                        smp_wmb(); \
-                (p) = (v); \
-        })
+        __rcu_assign_pointer((p), (v), __rcu)
+
+/**
+ * RCU_INIT_POINTER() - initialize an RCU protected pointer
+ *
+ * Initialize an RCU-protected pointer in such a way to avoid RCU-lockdep
+ * splats.
+ */
+#define RCU_INIT_POINTER(p, v) \
+                p = (typeof(*v) __force __rcu *)(v)
 
 /* Infrastructure to implement the synchronize_() primitives. */
 
@@ -494,26 +694,37 @@ struct rcu_synchronize {
 
 extern void wakeme_after_rcu(struct rcu_head  *head);
 
+#ifdef CONFIG_PREEMPT_RCU
+
 /**
- * call_rcu - Queue an RCU callback for invocation after a grace period.
+ * call_rcu() - Queue an RCU callback for invocation after a grace period.
  * @head: structure to be used for queueing the RCU updates.
- * @func: actual update function to be invoked after the grace period
+ * @func: actual callback function to be invoked after the grace period
  *
- * The update function will be invoked some time after a full grace
- * period elapses, in other words after all currently executing RCU
- * read-side critical sections have completed.  RCU read-side critical
+ * The callback function will be invoked some time after a full grace
+ * period elapses, in other words after all pre-existing RCU read-side
+ * critical sections have completed.  However, the callback function
+ * might well execute concurrently with RCU read-side critical sections
+ * that started after call_rcu() was invoked.  RCU read-side critical
  * sections are delimited by rcu_read_lock() and rcu_read_unlock(),
  * and may be nested.
  */
 extern void call_rcu(struct rcu_head *head,
                               void (*func)(struct rcu_head *head));
 
+#else /* #ifdef CONFIG_PREEMPT_RCU */
+
+/* In classic RCU, call_rcu() is just call_rcu_sched(). */
+#define call_rcu        call_rcu_sched
+
+#endif /* #else #ifdef CONFIG_PREEMPT_RCU */
+
 /**
- * call_rcu_bh - Queue an RCU for invocation after a quicker grace period.
+ * call_rcu_bh() - Queue an RCU for invocation after a quicker grace period.
  * @head: structure to be used for queueing the RCU updates.
- * @func: actual update function to be invoked after the grace period
+ * @func: actual callback function to be invoked after the grace period
  *
- * The update function will be invoked some time after a full grace
+ * The callback function will be invoked some time after a full grace
  * period elapses, in other words after all currently executing RCU
  * read-side critical sections have completed. call_rcu_bh() assumes
  * that the read-side critical sections end on completion of a softirq
@@ -566,37 +777,4 @@ static inline void debug_rcu_head_unqueue(struct rcu_head *head)
 }
 #endif  /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
 
-#ifndef CONFIG_PROVE_RCU
-#define __do_rcu_dereference_check(c) do { } while (0)
-#endif /* #ifdef CONFIG_PROVE_RCU */
-
-#define __rcu_dereference_index_check(p, c) \
-        ({ \
-                typeof(p) _________p1 = ACCESS_ONCE(p); \
-                __do_rcu_dereference_check(c); \
-                smp_read_barrier_depends(); \
-                (_________p1); \
-        })
-
-/**
- * rcu_dereference_index_check() - rcu_dereference for indices with debug checking
- * @p: The pointer to read, prior to dereferencing
- * @c: The conditions under which the dereference will take place
- *
- * Similar to rcu_dereference_check(), but omits the sparse checking.
- * This allows rcu_dereference_index_check() to be used on integers,
- * which can then be used as array indices.  Attempting to use
- * rcu_dereference_check() on an integer will give compiler warnings
- * because the sparse address-space mechanism relies on dereferencing
- * the RCU-protected pointer.  Dereferencing integers is not something
- * that even gcc will put up with.
- *
- * Note that this function does not implicitly check for RCU read-side
- * critical sections.  If this function gains lots of uses, it might
- * make sense to provide versions for each flavor of RCU, but it does
- * not make sense as of early 2010.
- */
-#define rcu_dereference_index_check(p, c) \
-        __rcu_dereference_index_check((p), (c))
-
 #endif /* __LINUX_RCUPDATE_H */
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index e2e893144a8..13877cb93a6 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -27,103 +27,101 @@
 
 #include <linux/cache.h>
 
-void rcu_sched_qs(int cpu);
-void rcu_bh_qs(int cpu);
-static inline void rcu_note_context_switch(int cpu)
-{
-        rcu_sched_qs(cpu);
-}
+#define rcu_init_sched()        do { } while (0)
 
-#define __rcu_read_lock()       preempt_disable()
-#define __rcu_read_unlock()     preempt_enable()
-#define __rcu_read_lock_bh()    local_bh_disable()
-#define __rcu_read_unlock_bh()  local_bh_enable()
-#define call_rcu_sched          call_rcu
+#ifdef CONFIG_TINY_RCU
 
-#define rcu_init_sched()        do { } while (0)
-extern void rcu_check_callbacks(int cpu, int user);
+static inline void synchronize_rcu_expedited(void)
+{
+        synchronize_sched();    /* Only one CPU, so pretty fast anyway!!! */
+}
 
-static inline int rcu_needs_cpu(int cpu)
+static inline void rcu_barrier(void)
 {
-        return 0;
+        rcu_barrier_sched();  /* Only one CPU, so only one list of callbacks! */
 }
 
-/*
- * Return the number of grace periods.
- */
-static inline long rcu_batches_completed(void)
+#else /* #ifdef CONFIG_TINY_RCU */
+
+void rcu_barrier(void);
+void synchronize_rcu_expedited(void);
+
+#endif /* #else #ifdef CONFIG_TINY_RCU */
+
+static inline void synchronize_rcu_bh(void)
 {
-        return 0;
+        synchronize_sched();
 }
 
-/*
- * Return the number of bottom-half grace periods.
- */
-static inline long rcu_batches_completed_bh(void)
+static inline void synchronize_rcu_bh_expedited(void)
 {
-        return 0;
+        synchronize_sched();
 }
 
-static inline void rcu_force_quiescent_state(void)
+#ifdef CONFIG_TINY_RCU
+
+static inline void rcu_preempt_note_context_switch(void)
 {
 }
 
-static inline void rcu_bh_force_quiescent_state(void)
+static inline void exit_rcu(void)
 {
 }
 
-static inline void rcu_sched_force_quiescent_state(void)
+static inline int rcu_needs_cpu(int cpu)
 {
+        return 0;
 }
 
-extern void synchronize_sched(void);
+#else /* #ifdef CONFIG_TINY_RCU */
+
+void rcu_preempt_note_context_switch(void);
+extern void exit_rcu(void);
+int rcu_preempt_needs_cpu(void);
 
-static inline void synchronize_rcu(void)
+static inline int rcu_needs_cpu(int cpu)
 {
-        synchronize_sched();
+        return rcu_preempt_needs_cpu();
 }
 
-static inline void synchronize_rcu_bh(void)
+#endif /* #else #ifdef CONFIG_TINY_RCU */
+
+static inline void rcu_note_context_switch(int cpu)
 {
-        synchronize_sched();
+        rcu_sched_qs(cpu);
+        rcu_preempt_note_context_switch();
 }
 
-static inline void synchronize_rcu_expedited(void)
+/*
+ * Return the number of grace periods.
+ */
+static inline long rcu_batches_completed(void)
 {
-        synchronize_sched();
+        return 0;
 }
 
-static inline void synchronize_rcu_bh_expedited(void)
+/*
+ * Return the number of bottom-half grace periods.
+ */
+static inline long rcu_batches_completed_bh(void)
 {
-        synchronize_sched();
+        return 0;
 }
 
-struct notifier_block;
-
-#ifdef CONFIG_NO_HZ
-
-extern void rcu_enter_nohz(void);
-extern void rcu_exit_nohz(void);
-
-#else /* #ifdef CONFIG_NO_HZ */
-
-static inline void rcu_enter_nohz(void)
+static inline void rcu_force_quiescent_state(void)
 {
 }
 
-static inline void rcu_exit_nohz(void)
+static inline void rcu_bh_force_quiescent_state(void)
 {
 }
 
-#endif /* #else #ifdef CONFIG_NO_HZ */
-
-static inline void exit_rcu(void)
+static inline void rcu_sched_force_quiescent_state(void)
 {
 }
 
-static inline int rcu_preempt_depth(void)
+static inline void rcu_cpu_stall_reset(void)
 {
-        return 0;
 }
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index c0ed1c056f2..95518e62879 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -30,64 +30,23 @@
 #ifndef __LINUX_RCUTREE_H
 #define __LINUX_RCUTREE_H
 
-struct notifier_block;
-
-extern void rcu_sched_qs(int cpu);
-extern void rcu_bh_qs(int cpu);
 extern void rcu_note_context_switch(int cpu);
 extern int rcu_needs_cpu(int cpu);
+extern void rcu_cpu_stall_reset(void);
 
 #ifdef CONFIG_TREE_PREEMPT_RCU
 
-extern void __rcu_read_lock(void);
-extern void __rcu_read_unlock(void);
-extern void synchronize_rcu(void);
 extern void exit_rcu(void);
 
-/*
- * Defined as macro as it is a very low level header
- * included from areas that don't even know about current
- */
-#define rcu_preempt_depth() (current->rcu_read_lock_nesting)
-
 #else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
 
-static inline void __rcu_read_lock(void)
-{
-        preempt_disable();
-}
-
-static inline void __rcu_read_unlock(void)
-{
-        preempt_enable();
-}
-
-#define synchronize_rcu synchronize_sched
-
 static inline void exit_rcu(void)
 {
 }
 
-static inline int rcu_preempt_depth(void)
-{
-        return 0;
-}
-
 #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
 
-static inline void __rcu_read_lock_bh(void)
-{
-        local_bh_disable();
-}
-static inline void __rcu_read_unlock_bh(void)
-{
-        local_bh_enable();
-}
-
-extern void call_rcu_sched(struct rcu_head *head,
-                           void (*func)(struct rcu_head *rcu));
 extern void synchronize_rcu_bh(void);
-extern void synchronize_sched(void);
 extern void synchronize_rcu_expedited(void);
 
 static inline void synchronize_rcu_bh_expedited(void)
@@ -95,7 +54,7 @@ static inline void synchronize_rcu_bh_expedited(void)
         synchronize_sched_expedited();
 }
 
-extern void rcu_check_callbacks(int cpu, int user);
+extern void rcu_barrier(void);
 
 extern long rcu_batches_completed(void);
 extern long rcu_batches_completed_bh(void);
@@ -104,18 +63,6 @@ extern void rcu_force_quiescent_state(void);
 extern void rcu_bh_force_quiescent_state(void);
 extern void rcu_sched_force_quiescent_state(void);
 
-#ifdef CONFIG_NO_HZ
-void rcu_enter_nohz(void);
-void rcu_exit_nohz(void);
-#else /* CONFIG_NO_HZ */
-static inline void rcu_enter_nohz(void)
-{
-}
-static inline void rcu_exit_nohz(void)
-{
-}
-#endif /* CONFIG_NO_HZ */
-
 /* A context switch is a grace period for RCU-sched and RCU-bh. */
 static inline int rcu_blocking_is_gp(void)
 {
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 1e2a6db2d7d..e18473f0eb7 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1202,11 +1202,13 @@ struct task_struct {
         unsigned int policy;
         cpumask_t cpus_allowed;
 
-#ifdef CONFIG_TREE_PREEMPT_RCU
+#ifdef CONFIG_PREEMPT_RCU
         int rcu_read_lock_nesting;
         char rcu_read_unlock_special;
-        struct rcu_node *rcu_blocked_node;
         struct list_head rcu_node_entry;
+#endif /* #ifdef CONFIG_PREEMPT_RCU */
+#ifdef CONFIG_TREE_PREEMPT_RCU
+        struct rcu_node *rcu_blocked_node;
 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
 
 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
@@ -1288,9 +1290,9 @@ struct task_struct {
         struct list_head cpu_timers[3];
 
 /* process credentials */
-        const struct cred *real_cred;   /* objective and real subjective task
+        const struct cred __rcu *real_cred; /* objective and real subjective task
                                          * credentials (COW) */
-        const struct cred *cred;        /* effective (overridable) subjective task
+        const struct cred __rcu *cred;  /* effective (overridable) subjective task
                                          * credentials (COW) */
         struct mutex cred_guard_mutex;  /* guard against foreign influences on
                                          * credential calculations
@@ -1418,7 +1420,7 @@ struct task_struct {
 #endif
 #ifdef CONFIG_CGROUPS
         /* Control Group info protected by css_set_lock */
-        struct css_set *cgroups;
+        struct css_set __rcu *cgroups;
         /* cg_list protected by css_set_lock and tsk->alloc_lock */
         struct list_head cg_list;
 #endif
@@ -1740,7 +1742,7 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *
 #define tsk_used_math(p) ((p)->flags & PF_USED_MATH)
 #define used_math() tsk_used_math(current)
 
-#ifdef CONFIG_TREE_PREEMPT_RCU
+#ifdef CONFIG_PREEMPT_RCU
 
 #define RCU_READ_UNLOCK_BLOCKED (1 << 0) /* blocked while in RCU read-side. */
 #define RCU_READ_UNLOCK_NEED_QS (1 << 1) /* RCU core needs CPU response. */
@@ -1749,7 +1751,9 @@ static inline void rcu_copy_process(struct task_struct *p)
 {
         p->rcu_read_lock_nesting = 0;
         p->rcu_read_unlock_special = 0;
+#ifdef CONFIG_TREE_PREEMPT_RCU
         p->rcu_blocked_node = NULL;
+#endif
         INIT_LIST_HEAD(&p->rcu_node_entry);
 }
 
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 4d5d2f546db..58971e891f4 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -108,19 +108,43 @@ static inline int srcu_read_lock_held(struct srcu_struct *sp)
 #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
 /**
- * srcu_dereference - fetch SRCU-protected pointer with checking
+ * srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing
+ * @p: the pointer to fetch and protect for later dereferencing
+ * @sp: pointer to the srcu_struct, which is used to check that we
+ *      really are in an SRCU read-side critical section.
+ * @c: condition to check for update-side use
  *
- * Makes rcu_dereference_check() do the dirty work.
+ * If PROVE_RCU is enabled, invoking this outside of an RCU read-side
+ * critical section will result in an RCU-lockdep splat, unless @c evaluates
+ * to 1.  The @c argument will normally be a logical expression containing
+ * lockdep_is_held() calls.
  */
-#define srcu_dereference(p, sp) \
-                rcu_dereference_check(p, srcu_read_lock_held(sp))
+#define srcu_dereference_check(p, sp, c) \
+        __rcu_dereference_check((p), srcu_read_lock_held(sp) || (c), __rcu)
+
+/**
+ * srcu_dereference - fetch SRCU-protected pointer for later dereferencing
+ * @p: the pointer to fetch and protect for later dereferencing
+ * @sp: pointer to the srcu_struct, which is used to check that we
+ *      really are in an SRCU read-side critical section.
+ *
+ * Makes rcu_dereference_check() do the dirty work.  If PROVE_RCU
+ * is enabled, invoking this outside of an RCU read-side critical
+ * section will result in an RCU-lockdep splat.
+ */
+#define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0)
 
 /**
  * srcu_read_lock - register a new reader for an SRCU-protected structure.
  * @sp: srcu_struct in which to register the new reader.
  *
  * Enter an SRCU read-side critical section.  Note that SRCU read-side
- * critical sections may be nested.
+ * critical sections may be nested.  However, it is illegal to
+ * call anything that waits on an SRCU grace period for the same
+ * srcu_struct, whether directly or indirectly.  Please note that
+ * one way to indirectly wait on an SRCU grace period is to acquire
+ * a mutex that is held elsewhere while calling synchronize_srcu() or
+ * synchronize_srcu_expedited().
  */
 static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
 {
diff --git a/include/linux/sunrpc/auth_gss.h b/include/linux/sunrpc/auth_gss.h
index 671538d25bc..8eee9dbbfe7 100644
--- a/include/linux/sunrpc/auth_gss.h
+++ b/include/linux/sunrpc/auth_gss.h
@@ -69,7 +69,7 @@ struct gss_cl_ctx {
         enum rpc_gss_proc       gc_proc;
         u32                     gc_seq;
         spinlock_t              gc_seq_lock;
-        struct gss_ctx          *gc_gss_ctx;
+        struct gss_ctx __rcu    *gc_gss_ctx;
         struct xdr_netobj       gc_wire_ctx;
         u32                     gc_win;
         unsigned long           gc_expiry;
@@ -80,7 +80,7 @@ struct gss_upcall_msg;
 struct gss_cred {
         struct rpc_cred         gc_base;
         enum rpc_gss_svc        gc_service;
-        struct gss_cl_ctx       *gc_ctx;
+        struct gss_cl_ctx __rcu *gc_ctx;
         struct gss_upcall_msg   *gc_upcall;
         unsigned long           gc_upcall_timestamp;
         unsigned char           gc_machine_cred : 1;
diff --git a/include/net/cls_cgroup.h b/include/net/cls_cgroup.h
index ef6c24a529e..a4dc5b027bd 100644
--- a/include/net/cls_cgroup.h
+++ b/include/net/cls_cgroup.h
@@ -51,7 +51,8 @@ static inline u32 task_cls_classid(struct task_struct *p)
                 return 0;
 
         rcu_read_lock();
-        id = rcu_dereference(net_cls_subsys_id);
+        id = rcu_dereference_index_check(net_cls_subsys_id,
+                                         rcu_read_lock_held());
         if (id >= 0)
                 classid = container_of(task_subsys_state(p, id),
                                        struct cgroup_cls_state, css)->classid;
diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index e624dae54fa..caf17db87db 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -75,7 +75,7 @@ struct nf_conntrack_helper;
 /* nf_conn feature for connections that have a helper */
 struct nf_conn_help {
         /* Helper. if any */
-        struct nf_conntrack_helper *helper;
+        struct nf_conntrack_helper __rcu *helper;
 
         union nf_conntrack_help help;