[RFC/INCOMPLETE 01/13] context_tracking: Add context_tracking_assert_state

[Andy Lutomirski <luto@kernel.org>]

This will let us sprinkle sanity checks around the kernel without
making too much of a mess.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 include/linux/context_tracking.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 2821838256b4..0fbea4b152e1 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -57,6 +57,13 @@ static inline void context_tracking_task_switch(struct task_struct *prev,
 	if (context_tracking_is_enabled())
 		__context_tracking_task_switch(prev, next);
 }
+
+static inline void context_tracking_assert_state(enum ctx_state state)
+{
+	rcu_lockdep_assert(!context_tracking_is_enabled() ||
+			   this_cpu_read(context_tracking.state) == state,
+			   "context tracking state was wrong");
+}
 #else
 static inline void user_enter(void) { }
 static inline void user_exit(void) { }
@@ -64,6 +71,7 @@ static inline enum ctx_state exception_enter(void) { return 0; }
 static inline void exception_exit(enum ctx_state prev_ctx) { }
 static inline void context_tracking_task_switch(struct task_struct *prev,
 						struct task_struct *next) { }
+static inline void context_tracking_assert_state(enum ctx_state state) { }
 #endif /* !CONFIG_CONTEXT_TRACKING */
 
 
-- 
2.4.3