2 files changed, 45 insertions, 0 deletions

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index d8b20bfd4795..f818dd165b44 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -193,6 +193,8 @@ extern void rcu_irq_enter(void);
 extern void rcu_irq_exit(void);
 extern void rcu_user_enter(void);
 extern void rcu_user_exit(void);
+extern void rcu_user_enter_after_irq(void);
+extern void rcu_user_exit_after_irq(void);
 extern void exit_rcu(void);
 
 /**
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index af0dc3472a4b..4138f59fa2f4 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -426,6 +426,27 @@ void rcu_user_enter(void)
 
 
 /**
+ * rcu_user_enter_after_irq - inform RCU that we are going to resume userspace
+ * after the current irq returns.
+ *
+ * This is similar to rcu_user_enter() but in the context of a non-nesting
+ * irq. After this call, RCU enters into idle mode when the interrupt
+ * returns.
+ */
+void rcu_user_enter_after_irq(void)
+{
+        unsigned long flags;
+        struct rcu_dynticks *rdtp;
+
+        local_irq_save(flags);
+        rdtp = &__get_cpu_var(rcu_dynticks);
+        /* Ensure this irq is interrupting a non-idle RCU state.  */
+        WARN_ON_ONCE(!(rdtp->dynticks_nesting & DYNTICK_TASK_MASK));
+        rdtp->dynticks_nesting = 1;
+        local_irq_restore(flags);
+}
+
+/**
  * rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle
  *
  * Exit from an interrupt handler, which might possibly result in entering
@@ -550,6 +571,28 @@ void rcu_user_exit(void)
 }
 
 /**
+ * rcu_user_exit_after_irq - inform RCU that we won't resume to userspace
+ * idle mode after the current non-nesting irq returns.
+ *
+ * This is similar to rcu_user_exit() but in the context of an irq.
+ * This is called when the irq has interrupted a userspace RCU idle mode
+ * context. When the current non-nesting interrupt returns after this call,
+ * the CPU won't restore the RCU idle mode.
+ */
+void rcu_user_exit_after_irq(void)
+{
+        unsigned long flags;
+        struct rcu_dynticks *rdtp;
+
+        local_irq_save(flags);
+        rdtp = &__get_cpu_var(rcu_dynticks);
+        /* Ensure we are interrupting an RCU idle mode. */
+        WARN_ON_ONCE(rdtp->dynticks_nesting & DYNTICK_TASK_NEST_MASK);
+        rdtp->dynticks_nesting += DYNTICK_TASK_EXIT_IDLE;
+        local_irq_restore(flags);
+}
+
+/**
  * rcu_irq_enter - inform RCU that current CPU is entering irq away from idle
  *
  * Enter an interrupt handler, which might possibly result in exiting