diff options
| -rw-r--r-- | arch/Kconfig | 10 | ||||
| -rw-r--r-- | include/linux/rcupdate.h | 9 | ||||
| -rw-r--r-- | init/Kconfig | 10 | ||||
| -rw-r--r-- | kernel/rcutree.c | 5 |
4 files changed, 33 insertions, 1 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index 72f2fa189cc5..1401a7587973 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -281,4 +281,14 @@ config SECCOMP_FILTER See Documentation/prctl/seccomp_filter.txt for details. +config HAVE_RCU_USER_QS + bool + help + Provide kernel entry/exit hooks necessary for userspace + RCU extended quiescent state. Syscalls need to be wrapped inside + rcu_user_exit()-rcu_user_enter() through the slow path using + TIF_NOHZ flag. Exceptions handlers must be wrapped as well. Irqs + are already protected inside rcu_irq_enter/rcu_irq_exit() but + preemption or signal handling on irq exit still need to be protected. + source "kernel/gcov/Kconfig" diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index f818dd165b44..f5034f22e94b 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -191,10 +191,19 @@ extern void rcu_idle_enter(void); extern void rcu_idle_exit(void); extern void rcu_irq_enter(void); extern void rcu_irq_exit(void); + +#ifdef CONFIG_RCU_USER_QS extern void rcu_user_enter(void); extern void rcu_user_exit(void); extern void rcu_user_enter_after_irq(void); extern void rcu_user_exit_after_irq(void); +#else +static inline void rcu_user_enter(void) { } +static inline void rcu_user_exit(void) { } +static inline void rcu_user_enter_after_irq(void) { } +static inline void rcu_user_exit_after_irq(void) { } +#endif /* CONFIG_RCU_USER_QS */ + extern void exit_rcu(void); /** diff --git a/init/Kconfig b/init/Kconfig index af6c7f8ba019..f6a1830165ce 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -441,6 +441,16 @@ config PREEMPT_RCU This option enables preemptible-RCU code that is common between the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations. +config RCU_USER_QS + bool "Consider userspace as in RCU extended quiescent state" + depends on HAVE_RCU_USER_QS && SMP + help + This option sets hooks on kernel / userspace boundaries and + puts RCU in extended quiescent state when the CPU runs in + userspace. It means that when a CPU runs in userspace, it is + excluded from the global RCU state machine and thus doesn't + to keep the timer tick on for RCU. + config RCU_FANOUT int "Tree-based hierarchical RCU fanout value" range 2 64 if 64BIT diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 4138f59fa2f4..79fa2db1595b 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -400,6 +400,7 @@ void rcu_idle_enter(void) } EXPORT_SYMBOL_GPL(rcu_idle_enter); +#ifdef CONFIG_RCU_USER_QS /** * rcu_user_enter - inform RCU that we are resuming userspace. * @@ -424,7 +425,6 @@ void rcu_user_enter(void) rcu_eqs_enter(1); } - /** * rcu_user_enter_after_irq - inform RCU that we are going to resume userspace * after the current irq returns. @@ -445,6 +445,7 @@ void rcu_user_enter_after_irq(void) rdtp->dynticks_nesting = 1; local_irq_restore(flags); } +#endif /* CONFIG_RCU_USER_QS */ /** * rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle @@ -548,6 +549,7 @@ void rcu_idle_exit(void) } EXPORT_SYMBOL_GPL(rcu_idle_exit); +#ifdef CONFIG_RCU_USER_QS /** * rcu_user_exit - inform RCU that we are exiting userspace. * @@ -591,6 +593,7 @@ void rcu_user_exit_after_irq(void) rdtp->dynticks_nesting += DYNTICK_TASK_EXIT_IDLE; local_irq_restore(flags); } +#endif /* CONFIG_RCU_USER_QS */ /** * rcu_irq_enter - inform RCU that current CPU is entering irq away from idle |