virtio_net: invoke softirqs after __napi_schedule

[linux-flexiantxendom0-3.2.10.git] / kernel / rcupdate.c

diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 0af1dc7..a86f174 100644 (file)
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -37,15 +37,20 @@
 #include <linux/smp.h>
 #include <linux/interrupt.h>
 #include <linux/sched.h>
-#include <asm/atomic.h>
+#include <linux/atomic.h>
 #include <linux/bitops.h>
 #include <linux/percpu.h>
 #include <linux/notifier.h>
 #include <linux/cpu.h>
 #include <linux/mutex.h>
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/hardirq.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/rcu.h>
+
+#include "rcu.h"
+
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 static struct lock_class_key rcu_lock_key;
 struct lockdep_map rcu_lock_map =
@@ -73,30 +78,44 @@ int debug_lockdep_rcu_enabled(void)
 EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
 
 /**
- * rcu_read_lock_bh_held - might we be in RCU-bh read-side critical section?
+ * rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section?
  *
  * 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.
+ * will show the situation.  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.
+ *
+ * Note that rcu_read_lock() is disallowed if the CPU is either idle or
+ * offline from an RCU perspective, so check for those as well.
  */
 int rcu_read_lock_bh_held(void)
 {
        if (!debug_lockdep_rcu_enabled())
                return 1;
+       if (rcu_is_cpu_idle())
+               return 0;
+       if (!rcu_lockdep_current_cpu_online())
+               return 0;
        return in_softirq() || irqs_disabled();
 }
 EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held);
 
 #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
+struct rcu_synchronize {
+       struct rcu_head head;
+       struct completion completion;
+};
+
 /*
  * Awaken the corresponding synchronize_rcu() instance now that a
  * grace period has elapsed.
  */
-void wakeme_after_rcu(struct rcu_head  *head)
+static void wakeme_after_rcu(struct rcu_head  *head)
 {
        struct rcu_synchronize *rcu;
 
@@ -104,6 +123,20 @@ void wakeme_after_rcu(struct rcu_head  *head)
        complete(&rcu->completion);
 }
 
+void wait_rcu_gp(call_rcu_func_t crf)
+{
+       struct rcu_synchronize rcu;
+
+       init_rcu_head_on_stack(&rcu.head);
+       init_completion(&rcu.completion);
+       /* Will wake me after RCU finished. */
+       crf(&rcu.head, wakeme_after_rcu);
+       /* Wait for it. */
+       wait_for_completion(&rcu.completion);
+       destroy_rcu_head_on_stack(&rcu.head);
+}
+EXPORT_SYMBOL_GPL(wait_rcu_gp);
+
 #ifdef CONFIG_PROVE_RCU
 /*
  * wrapper function to avoid #include problems.
@@ -140,10 +173,17 @@ static int rcuhead_fixup_init(void *addr, enum debug_obj_state state)
                 * 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.
+                * In !PREEMPT configurations, there is no way to tell if we are
+                * in a RCU read-side critical section or not, so we never
+                * attempt any fixup and just print a warning.
                 */
+#ifndef CONFIG_PREEMPT
+               WARN_ON_ONCE(1);
+               return 0;
+#endif
                if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
                    irqs_disabled()) {
-                       WARN_ON(1);
+                       WARN_ON_ONCE(1);
                        return 0;
                }
                rcu_barrier();
@@ -182,10 +222,17 @@ static int rcuhead_fixup_activate(void *addr, enum debug_obj_state state)
                 * 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.
+                * In !PREEMPT configurations, there is no way to tell if we are
+                * in a RCU read-side critical section or not, so we never
+                * attempt any fixup and just print a warning.
                 */
+#ifndef CONFIG_PREEMPT
+               WARN_ON_ONCE(1);
+               return 0;
+#endif
                if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
                    irqs_disabled()) {
-                       WARN_ON(1);
+                       WARN_ON_ONCE(1);
                        return 0;
                }
                rcu_barrier();
@@ -212,14 +259,17 @@ static int rcuhead_fixup_free(void *addr, enum debug_obj_state state)
                 * 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.
+                * In !PREEMPT configurations, there is no way to tell if we are
+                * in a RCU read-side critical section or not, so we never
+                * attempt any fixup and just print a warning.
                 */
 #ifndef CONFIG_PREEMPT
-               WARN_ON(1);
+               WARN_ON_ONCE(1);
                return 0;
-#else
+#endif
                if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
                    irqs_disabled()) {
-                       WARN_ON(1);
+                       WARN_ON_ONCE(1);
                        return 0;
                }
                rcu_barrier();
@@ -227,7 +277,6 @@ static int rcuhead_fixup_free(void *addr, enum debug_obj_state state)
                rcu_barrier_bh();
                debug_object_free(head, &rcuhead_debug_descr);
                return 1;
-#endif
        default:
                return 0;
        }
@@ -274,3 +323,13 @@ struct debug_obj_descr rcuhead_debug_descr = {
 };
 EXPORT_SYMBOL_GPL(rcuhead_debug_descr);
 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
+
+#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU) || defined(CONFIG_RCU_TRACE)
+void do_trace_rcu_torture_read(char *rcutorturename, struct rcu_head *rhp)
+{
+       trace_rcu_torture_read(rcutorturename, rhp);
+}
+EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read);
+#else
+#define do_trace_rcu_torture_read(rcutorturename, rhp) do { } while (0)
+#endif