migrate_disable() is called to disable migration in the kernel, and it is used togather with rcu_read_lock() oftenly. However, with PREEMPT_RCU disabled, it's unnecessary, as rcu_read_lock() will disable preemption, which will also disable migration. Introduce rcu_migrate_enable() and rcu_migrate_disable(), which will do the migration enable and disable only when the rcu_read_lock() can't do it. Signed-off-by: Menglong Dong --- include/linux/rcupdate.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 120536f4c6eb..0d9dbd90d025 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -72,6 +72,16 @@ static inline bool same_state_synchronize_rcu(unsigned long oldstate1, unsigned void __rcu_read_lock(void); void __rcu_read_unlock(void); +static inline void rcu_migrate_enable(void) +{ + migrate_enable(); +} + +static inline void rcu_migrate_disable(void) +{ + migrate_disable(); +} + /* * Defined as a macro as it is a very low level header included from * areas that don't even know about current. This gives the rcu_read_lock() @@ -105,6 +115,14 @@ static inline int rcu_preempt_depth(void) return 0; } +static inline void rcu_migrate_enable(void) +{ +} + +static inline void rcu_migrate_disable(void) +{ +} + #endif /* #else #ifdef CONFIG_PREEMPT_RCU */ #ifdef CONFIG_RCU_LAZY -- 2.50.1