tree/tiny rcu: Add debug RCU head objects
[linux-2.6.git] / kernel / rcupdate.c
index 72a8dc9..4d16983 100644 (file)
@@ -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 */