[1/6] rcu,nohz: add state parameter to context_tracking_user_enter/exit

Commit Message

Rik van Riel Feb. 9, 2015, 4:04 p.m. UTC

From: Rik van Riel <[e-mail]>

Add the expected ctx_state as a parameter to context_tracking_user_enter
and context_tracking_user_exit, allowing the same functions to not just
track kernel <> user space switching, but also kernel <> guest transitions.

Catalin, Will: this patch and the next one break ARM, entry.S needs to be
modified to add the IN_USER parameter to context_tracking_enter & _exit.

Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Rik van Riel <[e-mail]>
---
 include/linux/context_tracking.h | 12 ++++++------
 kernel/context_tracking.c        | 10 +++++-----
 2 files changed, 11 insertions(+), 11 deletions(-)

Patch

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 37b81bd51ec0..bd9f000fc98d 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -10,21 +10,21 @@ 
 #ifdef CONFIG_CONTEXT_TRACKING
 extern void context_tracking_cpu_set(int cpu);
 
-extern void context_tracking_user_enter(void);
-extern void context_tracking_user_exit(void);
+extern void context_tracking_user_enter(enum ctx_state state);
+extern void context_tracking_user_exit(enum ctx_state state);
 extern void __context_tracking_task_switch(struct task_struct *prev,
 					   struct task_struct *next);
 
 static inline void user_enter(void)
 {
 	if (context_tracking_is_enabled())
-		context_tracking_user_enter();
+		context_tracking_user_enter(IN_USER);
 
 }
 static inline void user_exit(void)
 {
 	if (context_tracking_is_enabled())
-		context_tracking_user_exit();
+		context_tracking_user_exit(IN_USER);
 }
 
 static inline enum ctx_state exception_enter(void)
@@ -35,7 +35,7 @@  static inline enum ctx_state exception_enter(void)
 		return 0;
 
 	prev_ctx = this_cpu_read(context_tracking.state);
-	context_tracking_user_exit();
+	context_tracking_user_exit(prev_ctx);
 
 	return prev_ctx;
 }
@@ -44,7 +44,7 @@  static inline void exception_exit(enum ctx_state prev_ctx)
 {
 	if (context_tracking_is_enabled()) {
 		if (prev_ctx == IN_USER)
-			context_tracking_user_enter();
+			context_tracking_user_enter(prev_ctx);
 	}
 }
 
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 937ecdfdf258..4c010787c9ec 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -47,7 +47,7 @@  void context_tracking_cpu_set(int cpu)
  * to execute won't use any RCU read side critical section because this
  * function sets RCU in extended quiescent state.
  */
-void context_tracking_user_enter(void)
+void context_tracking_user_enter(enum ctx_state state)
 {
 	unsigned long flags;
 
@@ -75,7 +75,7 @@  void context_tracking_user_enter(void)
 	WARN_ON_ONCE(!current->mm);
 
 	local_irq_save(flags);
-	if ( __this_cpu_read(context_tracking.state) != IN_USER) {
+	if ( __this_cpu_read(context_tracking.state) != state) {
 		if (__this_cpu_read(context_tracking.active)) {
 			trace_user_enter(0);
 			/*
@@ -101,7 +101,7 @@  void context_tracking_user_enter(void)
 		 * OTOH we can spare the calls to vtime and RCU when context_tracking.active
 		 * is false because we know that CPU is not tickless.
 		 */
-		__this_cpu_write(context_tracking.state, IN_USER);
+		__this_cpu_write(context_tracking.state, state);
 	}
 	local_irq_restore(flags);
 }
@@ -118,7 +118,7 @@  NOKPROBE_SYMBOL(context_tracking_user_enter);
  * This call supports re-entrancy. This way it can be called from any exception
  * handler without needing to know if we came from userspace or not.
  */
-void context_tracking_user_exit(void)
+void context_tracking_user_exit(enum ctx_state state)
 {
 	unsigned long flags;
 
@@ -129,7 +129,7 @@  void context_tracking_user_exit(void)
 		return;
 
 	local_irq_save(flags);
-	if (__this_cpu_read(context_tracking.state) == IN_USER) {
+	if (__this_cpu_read(context_tracking.state) == state) {
 		if (__this_cpu_read(context_tracking.active)) {
 			/*
 			 * We are going to run code that may use RCU. Inform