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:
  Revert "net: Make accesses to ->br_port safe for sparse RCU"
  mce: convert to rcu_dereference_index_check()
  net: Make accesses to ->br_port safe for sparse RCU
  vfs: add fs.h to define struct file
  lockdep: Add an in_workqueue_context() lockdep-based test function
  rcu: add __rcu API for later sparse checking
  rcu: add an rcu_dereference_index_check()
  tree/tiny rcu: Add debug RCU head objects
  mm: remove all rcu head initializations
  fs: remove all rcu head initializations, except on_stack initializations
  powerpc: remove all rcu head initializations

4 files changed, 179 insertions, 0 deletions

diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 72a8dc9567f5..4d169835fb36 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -114,3 +114,163 @@ int rcu_my_thread_group_empty(void)
 }
 EXPORT_SYMBOL_GPL(rcu_my_thread_group_empty);
 #endif /* #ifdef CONFIG_PROVE_RCU */
+
+#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
+static inline void debug_init_rcu_head(struct rcu_head *head)
+{
+        debug_object_init(head, &rcuhead_debug_descr);
+}
+
+static inline void debug_rcu_head_free(struct rcu_head *head)
+{
+        debug_object_free(head, &rcuhead_debug_descr);
+}
+
+/*
+ * fixup_init is called when:
+ * - an active object is initialized
+ */
+static int rcuhead_fixup_init(void *addr, enum debug_obj_state state)
+{
+        struct rcu_head *head = addr;
+
+        switch (state) {
+        case ODEBUG_STATE_ACTIVE:
+                /*
+                 * Ensure that queued callbacks are all executed.
+                 * If we detect that we are nested in a RCU read-side critical
+                 * section, we should simply fail, otherwise we would deadlock.
+                 */
+                if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
+                    irqs_disabled()) {
+                        WARN_ON(1);
+                        return 0;
+                }
+                rcu_barrier();
+                rcu_barrier_sched();
+                rcu_barrier_bh();
+                debug_object_init(head, &rcuhead_debug_descr);
+                return 1;
+        default:
+                return 0;
+        }
+}
+
+/*
+ * fixup_activate is called when:
+ * - an active object is activated
+ * - an unknown object is activated (might be a statically initialized object)
+ * Activation is performed internally by call_rcu().
+ */
+static int rcuhead_fixup_activate(void *addr, enum debug_obj_state state)
+{
+        struct rcu_head *head = addr;
+
+        switch (state) {
+
+        case ODEBUG_STATE_NOTAVAILABLE:
+                /*
+                 * This is not really a fixup. We just make sure that it is
+                 * tracked in the object tracker.
+                 */
+                debug_object_init(head, &rcuhead_debug_descr);
+                debug_object_activate(head, &rcuhead_debug_descr);
+                return 0;
+
+        case ODEBUG_STATE_ACTIVE:
+                /*
+                 * Ensure that queued callbacks are all executed.
+                 * If we detect that we are nested in a RCU read-side critical
+                 * section, we should simply fail, otherwise we would deadlock.
+                 */
+                if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
+                    irqs_disabled()) {
+                        WARN_ON(1);
+                        return 0;
+                }
+                rcu_barrier();
+                rcu_barrier_sched();
+                rcu_barrier_bh();
+                debug_object_activate(head, &rcuhead_debug_descr);
+                return 1;
+        default:
+                return 0;
+        }
+}
+
+/*
+ * fixup_free is called when:
+ * - an active object is freed
+ */
+static int rcuhead_fixup_free(void *addr, enum debug_obj_state state)
+{
+        struct rcu_head *head = addr;
+
+        switch (state) {
+        case ODEBUG_STATE_ACTIVE:
+                /*
+                 * Ensure that queued callbacks are all executed.
+                 * If we detect that we are nested in a RCU read-side critical
+                 * section, we should simply fail, otherwise we would deadlock.
+                 */
+#ifndef CONFIG_PREEMPT
+                WARN_ON(1);
+                return 0;
+#else
+                if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
+                    irqs_disabled()) {
+                        WARN_ON(1);
+                        return 0;
+                }
+                rcu_barrier();
+                rcu_barrier_sched();
+                rcu_barrier_bh();
+                debug_object_free(head, &rcuhead_debug_descr);
+                return 1;
+#endif
+        default:
+                return 0;
+        }
+}
+
+/**
+ * init_rcu_head_on_stack() - initialize on-stack rcu_head for debugobjects
+ * @head: pointer to rcu_head structure to be initialized
+ *
+ * This function informs debugobjects of a new rcu_head structure that
+ * has been allocated as an auto variable on the stack.  This function
+ * is not required for rcu_head structures that are statically defined or
+ * that are dynamically allocated on the heap.  This function has no
+ * effect for !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds.
+ */
+void init_rcu_head_on_stack(struct rcu_head *head)
+{
+        debug_object_init_on_stack(head, &rcuhead_debug_descr);
+}
+EXPORT_SYMBOL_GPL(init_rcu_head_on_stack);
+
+/**
+ * destroy_rcu_head_on_stack() - destroy on-stack rcu_head for debugobjects
+ * @head: pointer to rcu_head structure to be initialized
+ *
+ * This function informs debugobjects that an on-stack rcu_head structure
+ * is about to go out of scope.  As with init_rcu_head_on_stack(), this
+ * function is not required for rcu_head structures that are statically
+ * defined or that are dynamically allocated on the heap.  Also as with
+ * init_rcu_head_on_stack(), this function has no effect for
+ * !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds.
+ */
+void destroy_rcu_head_on_stack(struct rcu_head *head)
+{
+        debug_object_free(head, &rcuhead_debug_descr);
+}
+EXPORT_SYMBOL_GPL(destroy_rcu_head_on_stack);
+
+struct debug_obj_descr rcuhead_debug_descr = {
+        .name = "rcu_head",
+        .fixup_init = rcuhead_fixup_init,
+        .fixup_activate = rcuhead_fixup_activate,
+        .fixup_free = rcuhead_fixup_free,
+};
+EXPORT_SYMBOL_GPL(rcuhead_debug_descr);
+#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c
index 38729d3cd236..196ec02f8be0 100644
--- a/kernel/rcutiny.c
+++ b/kernel/rcutiny.c
@@ -169,6 +169,7 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp)
         while (list) {
                 next = list->next;
                 prefetch(next);
+                debug_rcu_head_unqueue(list);
                 list->func(list);
                 list = next;
         }
@@ -211,6 +212,7 @@ static void __call_rcu(struct rcu_head *head,
 {
         unsigned long flags;
 
+        debug_rcu_head_queue(head);
         head->func = func;
         head->next = NULL;
 
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index d4437345706f..d5bc43976c5a 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1112,6 +1112,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
         while (list) {
                 next = list->next;
                 prefetch(next);
+                debug_rcu_head_unqueue(list);
                 list->func(list);
                 list = next;
                 if (++count >= rdp->blimit)
@@ -1388,6 +1389,7 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
         unsigned long flags;
         struct rcu_data *rdp;
 
+        debug_rcu_head_queue(head);
         head->func = func;
         head->next = NULL;
 
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 327d2deb4451..59fef1531dd2 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -68,6 +68,21 @@ struct workqueue_struct {
 #endif
 };
 
+#ifdef CONFIG_LOCKDEP
+/**
+ * in_workqueue_context() - in context of specified workqueue?
+ * @wq: the workqueue of interest
+ *
+ * Checks lockdep state to see if the current task is executing from
+ * within a workqueue item.  This function exists only if lockdep is
+ * enabled.
+ */
+int in_workqueue_context(struct workqueue_struct *wq)
+{
+        return lock_is_held(&wq->lockdep_map);
+}
+#endif
+
 #ifdef CONFIG_DEBUG_OBJECTS_WORK
 
 static struct debug_obj_descr work_debug_descr;