context_tracking: Switch to new static_branch API

This is much less error-prone than the old code.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/812df7e64f120c5c7c08481f36a8caa9f53b2199.1447361906.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h
index ee956c528fabf78cefcb58a67ff38aaaf621fcaf..1d34fe68f48ad3bea0c98e2eadbabae0aeb152d9 100644 (file)
--- a/include/linux/context_tracking_state.h
+++ b/include/linux/context_tracking_state.h
@@ -22,12 +22,12 @@ struct context_tracking {
 };
 
 #ifdef CONFIG_CONTEXT_TRACKING
-extern struct static_key context_tracking_enabled;
+extern struct static_key_false context_tracking_enabled;
 DECLARE_PER_CPU(struct context_tracking, context_tracking);
 
 static inline bool context_tracking_is_enabled(void)
 {
-       return static_key_false(&context_tracking_enabled);
+       return static_branch_unlikely(&context_tracking_enabled);
 }
 
 static inline bool context_tracking_cpu_is_enabled(void)

diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index d8560ee3bab788c15be6d1be8eb610473fc5c4b5..9ad37b9e44a7034d887fe1eda6650070490ee2d5 100644 (file)
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -24,7 +24,7 @@
 #define CREATE_TRACE_POINTS
 #include <trace/events/context_tracking.h>
 
-struct static_key context_tracking_enabled = STATIC_KEY_INIT_FALSE;
+DEFINE_STATIC_KEY_FALSE(context_tracking_enabled);
 EXPORT_SYMBOL_GPL(context_tracking_enabled);
 
 DEFINE_PER_CPU(struct context_tracking, context_tracking);
@@ -191,7 +191,7 @@ void __init context_tracking_cpu_set(int cpu)
 
        if (!per_cpu(context_tracking.active, cpu)) {
                per_cpu(context_tracking.active, cpu) = true;
-               static_key_slow_inc(&context_tracking_enabled);
+               static_branch_inc(&context_tracking_enabled);
        }
 
        if (initialized)