Merge branches 'fixes.2015.07.22a' and 'initexp.2015.08.04a' into HEAD

[firefly-linux-kernel-4.4.55.git] / kernel / rcu / tree.c

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 439112e9d1b3e77298ca82f86fb4f0e225765feb..9f75f25cc5d92667c27d70dd1b1a6091b42fbceb 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -646,12 +646,12 @@ static void rcu_eqs_enter_common(long long oldval, bool user)
         * It is illegal to enter an extended quiescent state while
         * in an RCU read-side critical section.
         */
-       rcu_lockdep_assert(!lock_is_held(&rcu_lock_map),
-                          "Illegal idle entry in RCU read-side critical section.");
-       rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map),
-                          "Illegal idle entry in RCU-bh read-side critical section.");
-       rcu_lockdep_assert(!lock_is_held(&rcu_sched_lock_map),
-                          "Illegal idle entry in RCU-sched read-side critical section.");
+       RCU_LOCKDEP_WARN(lock_is_held(&rcu_lock_map),
+                        "Illegal idle entry in RCU read-side critical section.");
+       RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map),
+                        "Illegal idle entry in RCU-bh read-side critical section.");
+       RCU_LOCKDEP_WARN(lock_is_held(&rcu_sched_lock_map),
+                        "Illegal idle entry in RCU-sched read-side critical section.");
 }
 
 /*
@@ -698,7 +698,7 @@ void rcu_idle_enter(void)
 }
 EXPORT_SYMBOL_GPL(rcu_idle_enter);
 
-#ifdef CONFIG_RCU_USER_QS
+#ifdef CONFIG_NO_HZ_FULL
 /**
  * rcu_user_enter - inform RCU that we are resuming userspace.
  *
@@ -711,7 +711,7 @@ void rcu_user_enter(void)
 {
        rcu_eqs_enter(1);
 }
-#endif /* CONFIG_RCU_USER_QS */
+#endif /* CONFIG_NO_HZ_FULL */
 
 /**
  * rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle
@@ -825,7 +825,7 @@ void rcu_idle_exit(void)
 }
 EXPORT_SYMBOL_GPL(rcu_idle_exit);
 
-#ifdef CONFIG_RCU_USER_QS
+#ifdef CONFIG_NO_HZ_FULL
 /**
  * rcu_user_exit - inform RCU that we are exiting userspace.
  *
@@ -836,7 +836,7 @@ void rcu_user_exit(void)
 {
        rcu_eqs_exit(1);
 }
-#endif /* CONFIG_RCU_USER_QS */
+#endif /* CONFIG_NO_HZ_FULL */
 
 /**
  * rcu_irq_enter - inform RCU that current CPU is entering irq away from idle
@@ -975,9 +975,9 @@ bool notrace rcu_is_watching(void)
 {
        bool ret;
 
-       preempt_disable();
+       preempt_disable_notrace();
        ret = __rcu_is_watching();
-       preempt_enable();
+       preempt_enable_notrace();
        return ret;
 }
 EXPORT_SYMBOL_GPL(rcu_is_watching);
@@ -3180,10 +3180,10 @@ static inline int rcu_blocking_is_gp(void)
  */
 void synchronize_sched(void)
 {
-       rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) &&
-                          !lock_is_held(&rcu_lock_map) &&
-                          !lock_is_held(&rcu_sched_lock_map),
-                          "Illegal synchronize_sched() in RCU-sched read-side critical section");
+       RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map) ||
+                        lock_is_held(&rcu_lock_map) ||
+                        lock_is_held(&rcu_sched_lock_map),
+                        "Illegal synchronize_sched() in RCU-sched read-side critical section");
        if (rcu_blocking_is_gp())
                return;
        if (rcu_gp_is_expedited())
@@ -3207,10 +3207,10 @@ EXPORT_SYMBOL_GPL(synchronize_sched);
  */
 void synchronize_rcu_bh(void)
 {
-       rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) &&
-                          !lock_is_held(&rcu_lock_map) &&
-                          !lock_is_held(&rcu_sched_lock_map),
-                          "Illegal synchronize_rcu_bh() in RCU-bh read-side critical section");
+       RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map) ||
+                        lock_is_held(&rcu_lock_map) ||
+                        lock_is_held(&rcu_sched_lock_map),
+                        "Illegal synchronize_rcu_bh() in RCU-bh read-side critical section");
        if (rcu_blocking_is_gp())
                return;
        if (rcu_gp_is_expedited())
@@ -3272,6 +3272,58 @@ void cond_synchronize_rcu(unsigned long oldstate)
 }
 EXPORT_SYMBOL_GPL(cond_synchronize_rcu);
 
+/**
+ * get_state_synchronize_sched - Snapshot current RCU-sched state
+ *
+ * Returns a cookie that is used by a later call to cond_synchronize_sched()
+ * to determine whether or not a full grace period has elapsed in the
+ * meantime.
+ */
+unsigned long get_state_synchronize_sched(void)
+{
+       /*
+        * Any prior manipulation of RCU-protected data must happen
+        * before the load from ->gpnum.
+        */
+       smp_mb();  /* ^^^ */
+
+       /*
+        * Make sure this load happens before the purportedly
+        * time-consuming work between get_state_synchronize_sched()
+        * and cond_synchronize_sched().
+        */
+       return smp_load_acquire(&rcu_sched_state.gpnum);
+}
+EXPORT_SYMBOL_GPL(get_state_synchronize_sched);
+
+/**
+ * cond_synchronize_sched - Conditionally wait for an RCU-sched grace period
+ *
+ * @oldstate: return value from earlier call to get_state_synchronize_sched()
+ *
+ * If a full RCU-sched grace period has elapsed since the earlier call to
+ * get_state_synchronize_sched(), just return.  Otherwise, invoke
+ * synchronize_sched() to wait for a full grace period.
+ *
+ * Yes, this function does not take counter wrap into account.  But
+ * counter wrap is harmless.  If the counter wraps, we have waited for
+ * more than 2 billion grace periods (and way more on a 64-bit system!),
+ * so waiting for one additional grace period should be just fine.
+ */
+void cond_synchronize_sched(unsigned long oldstate)
+{
+       unsigned long newstate;
+
+       /*
+        * Ensure that this load happens before any RCU-destructive
+        * actions the caller might carry out after we return.
+        */
+       newstate = smp_load_acquire(&rcu_sched_state.completed);
+       if (ULONG_CMP_GE(oldstate, newstate))
+               synchronize_sched();
+}
+EXPORT_SYMBOL_GPL(cond_synchronize_sched);
+
 /* Adjust sequence number for start of update-side operation. */
 static void rcu_seq_start(unsigned long *sp)
 {