[patch 10/24] sched/smt: Expose sched_smt_present static key

[Thomas Gleixner]

Make the scheduler's 'sched_smt_present' static key globaly available, so
it can be used in the x86 speculation control code.

Provide a query function and a stub for the CONFIG_SMP=n case.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
 include/linux/sched/topology.h |    9 +++++++++
 kernel/sched/sched.h           |    3 ---
 2 files changed, 9 insertions(+), 3 deletions(-)

--- a/include/linux/sched/topology.h
+++ b/include/linux/sched/topology.h
@@ -34,10 +34,19 @@
 #define SD_NUMA			0x4000	/* cross-node balancing */
 
 #ifdef CONFIG_SCHED_SMT
+extern struct static_key_false sched_smt_present;
+
+static __always_inline bool sched_smt_active(void)
+{
+	return static_branch_likely(&sched_smt_present);
+}
+
 static inline int cpu_smt_flags(void)
 {
 	return SD_SHARE_CPUCAPACITY | SD_SHARE_PKG_RESOURCES;
 }
+#else
+static inline bool sched_smt_active(void) { return false; }
 #endif
 
 #ifdef CONFIG_SCHED_MC
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -941,9 +941,6 @@ static inline int cpu_of(struct rq *rq)
 
 
 #ifdef CONFIG_SCHED_SMT
-
-extern struct static_key_false sched_smt_present;
-
 extern void __update_idle_core(struct rq *rq);
 
 static inline void update_idle_core(struct rq *rq)