Merge branch 'wip-2.6.34' into old-private-masterarchived-private-master

1 files changed, 57 insertions, 109 deletions

diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 400183346ad2..49d808e833b0 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -45,143 +45,91 @@
 #include <linux/mutex.h>
 #include <linux/module.h>
 #include <linux/kernel_stat.h>
+#include <linux/hardirq.h>
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 static struct lock_class_key rcu_lock_key;
 struct lockdep_map rcu_lock_map =
         STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key);
 EXPORT_SYMBOL_GPL(rcu_lock_map);
-#endif
 
-int rcu_scheduler_active __read_mostly;
+static struct lock_class_key rcu_bh_lock_key;
+struct lockdep_map rcu_bh_lock_map =
+        STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_bh", &rcu_bh_lock_key);
+EXPORT_SYMBOL_GPL(rcu_bh_lock_map);
 
-/*
- * Awaken the corresponding synchronize_rcu() instance now that a
- * grace period has elapsed.
- */
-void wakeme_after_rcu(struct rcu_head  *head)
-{
-        struct rcu_synchronize *rcu;
+static struct lock_class_key rcu_sched_lock_key;
+struct lockdep_map rcu_sched_lock_map =
+        STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_sched", &rcu_sched_lock_key);
+EXPORT_SYMBOL_GPL(rcu_sched_lock_map);
+#endif
 
-        rcu = container_of(head, struct rcu_synchronize, head);
-        complete(&rcu->completion);
-}
+int rcu_scheduler_active __read_mostly;
+EXPORT_SYMBOL_GPL(rcu_scheduler_active);
 
-#ifdef CONFIG_TREE_PREEMPT_RCU
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
 
-/**
- * synchronize_rcu - wait until a grace period has elapsed.
- *
- * Control will return to the caller some time after a full grace
- * period has elapsed, in other words after all currently executing RCU
- * read-side critical sections have completed.  RCU read-side critical
- * sections are delimited by rcu_read_lock() and rcu_read_unlock(),
- * and may be nested.
- */
-void synchronize_rcu(void)
+int debug_lockdep_rcu_enabled(void)
 {
-        struct rcu_synchronize rcu;
-
-        if (!rcu_scheduler_active)
-                return;
-
-        init_completion(&rcu.completion);
-        /* Will wake me after RCU finished. */
-        call_rcu(&rcu.head, wakeme_after_rcu);
-        /* Wait for it. */
-        wait_for_completion(&rcu.completion);
+        return rcu_scheduler_active && debug_locks &&
+               current->lockdep_recursion == 0;
 }
-EXPORT_SYMBOL_GPL(synchronize_rcu);
-
-#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
+EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
 
 /**
- * synchronize_sched - wait until an rcu-sched grace period has elapsed.
- *
- * Control will return to the caller some time after a full rcu-sched
- * grace period has elapsed, in other words after all currently executing
- * rcu-sched read-side critical sections have completed.   These read-side
- * critical sections are delimited by rcu_read_lock_sched() and
- * rcu_read_unlock_sched(), and may be nested.  Note that preempt_disable(),
- * local_irq_disable(), and so on may be used in place of
- * rcu_read_lock_sched().
+ * rcu_read_lock_bh_held - might we be in RCU-bh read-side critical section?
  *
- * This means that all preempt_disable code sequences, including NMI and
- * hardware-interrupt handlers, in progress on entry will have completed
- * before this primitive returns.  However, this does not guarantee that
- * softirq handlers will have completed, since in some kernels, these
- * handlers can run in process context, and can block.
+ * Check for bottom half being disabled, which covers both the
+ * CONFIG_PROVE_RCU and not cases.  Note that if someone uses
+ * rcu_read_lock_bh(), but then later enables BH, lockdep (if enabled)
+ * will show the situation.
  *
- * This primitive provides the guarantees made by the (now removed)
- * synchronize_kernel() API.  In contrast, synchronize_rcu() only
- * guarantees that rcu_read_lock() sections will have completed.
- * In "classic RCU", these two guarantees happen to be one and
- * the same, but can differ in realtime RCU implementations.
+ * Check debug_lockdep_rcu_enabled() to prevent false positives during boot.
  */
-void synchronize_sched(void)
+int rcu_read_lock_bh_held(void)
 {
-        struct rcu_synchronize rcu;
-
-        if (rcu_blocking_is_gp())
-                return;
-
-        init_completion(&rcu.completion);
-        /* Will wake me after RCU finished. */
-        call_rcu_sched(&rcu.head, wakeme_after_rcu);
-        /* Wait for it. */
-        wait_for_completion(&rcu.completion);
+        if (!debug_lockdep_rcu_enabled())
+                return 1;
+        return in_softirq();
 }
-EXPORT_SYMBOL_GPL(synchronize_sched);
-
-/**
- * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed.
- *
- * Control will return to the caller some time after a full rcu_bh grace
- * period has elapsed, in other words after all currently executing rcu_bh
- * read-side critical sections have completed.  RCU read-side critical
- * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(),
- * and may be nested.
- */
-void synchronize_rcu_bh(void)
-{
-        struct rcu_synchronize rcu;
+EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held);
 
-        if (rcu_blocking_is_gp())
-                return;
+#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
-        init_completion(&rcu.completion);
-        /* Will wake me after RCU finished. */
-        call_rcu_bh(&rcu.head, wakeme_after_rcu);
-        /* Wait for it. */
-        wait_for_completion(&rcu.completion);
-}
-EXPORT_SYMBOL_GPL(synchronize_rcu_bh);
-
-static int __cpuinit rcu_barrier_cpu_hotplug(struct notifier_block *self,
-                unsigned long action, void *hcpu)
+/*
+ * This function is invoked towards the end of the scheduler's initialization
+ * process.  Before this is called, the idle task might contain
+ * RCU read-side critical sections (during which time, this idle
+ * task is booting the system).  After this function is called, the
+ * idle tasks are prohibited from containing RCU read-side critical
+ * sections.
+ */
+void rcu_scheduler_starting(void)
 {
-        return rcu_cpu_notify(self, action, hcpu);
+        WARN_ON(num_online_cpus() != 1);
+        WARN_ON(nr_context_switches() > 0);
+        rcu_scheduler_active = 1;
 }
 
-void __init rcu_init(void)
+/*
+ * Awaken the corresponding synchronize_rcu() instance now that a
+ * grace period has elapsed.
+ */
+void wakeme_after_rcu(struct rcu_head  *head)
 {
-        int i;
-
-        __rcu_init();
-        cpu_notifier(rcu_barrier_cpu_hotplug, 0);
+        struct rcu_synchronize *rcu;
 
-        /*
-         * We don't need protection against CPU-hotplug here because
-         * this is called early in boot, before either interrupts
-         * or the scheduler are operational.
-         */
-        for_each_online_cpu(i)
-                rcu_barrier_cpu_hotplug(NULL, CPU_UP_PREPARE, (void *)(long)i);
+        rcu = container_of(head, struct rcu_synchronize, head);
+        complete(&rcu->completion);
 }
 
-void rcu_scheduler_starting(void)
+#ifdef CONFIG_PROVE_RCU
+/*
+ * wrapper function to avoid #include problems.
+ */
+int rcu_my_thread_group_empty(void)
 {
-        WARN_ON(num_online_cpus() != 1);
-        WARN_ON(nr_context_switches() > 0);
-        rcu_scheduler_active = 1;
+        return thread_group_empty(current);
 }
+EXPORT_SYMBOL_GPL(rcu_my_thread_group_empty);
+#endif /* #ifdef CONFIG_PROVE_RCU */