diff options
Diffstat (limited to 'include/linux/rcupreempt.h')
| -rw-r--r-- | include/linux/rcupreempt.h | 62 |
1 files changed, 22 insertions, 40 deletions
diff --git a/include/linux/rcupreempt.h b/include/linux/rcupreempt.h index 3e05c09b54a..fce522782ff 100644 --- a/include/linux/rcupreempt.h +++ b/include/linux/rcupreempt.h @@ -36,34 +36,19 @@ #include <linux/cache.h> #include <linux/spinlock.h> #include <linux/threads.h> -#include <linux/percpu.h> +#include <linux/smp.h> #include <linux/cpumask.h> #include <linux/seqlock.h> -struct rcu_dyntick_sched { - int dynticks; - int dynticks_snap; - int sched_qs; - int sched_qs_snap; - int sched_dynticks_snap; -}; - -DECLARE_PER_CPU(struct rcu_dyntick_sched, rcu_dyntick_sched); - -static inline void rcu_qsctr_inc(int cpu) -{ - struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu); - - rdssp->sched_qs++; -} -#define rcu_bh_qsctr_inc(cpu) +extern void rcu_qsctr_inc(int cpu); +static inline void rcu_bh_qsctr_inc(int cpu) { } /* * Someone might want to pass call_rcu_bh as a function pointer. * So this needs to just be a rename and not a macro function. * (no parentheses) */ -#define call_rcu_bh call_rcu +#define call_rcu_bh call_rcu /** * call_rcu_sched - Queue RCU callback for invocation after sched grace period. @@ -117,29 +102,26 @@ extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu); struct softirq_action; #ifdef CONFIG_NO_HZ +extern void rcu_enter_nohz(void); +extern void rcu_exit_nohz(void); +#else +# define rcu_enter_nohz() do { } while (0) +# define rcu_exit_nohz() do { } while (0) +#endif -static inline void rcu_enter_nohz(void) -{ - static DEFINE_RATELIMIT_STATE(rs, 10 * HZ, 1); - - smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ - __get_cpu_var(rcu_dyntick_sched).dynticks++; - WARN_ON_RATELIMIT(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1, &rs); -} - -static inline void rcu_exit_nohz(void) +/* + * A context switch is a grace period for rcupreempt synchronize_rcu() + * only during early boot, before the scheduler has been initialized. + * So, how the heck do we get a context switch? Well, if the caller + * invokes synchronize_rcu(), they are willing to accept a context + * switch, so we simply pretend that one happened. + * + * After boot, there might be a blocked or preempted task in an RCU + * read-side critical section, so we cannot then take the fastpath. + */ +static inline int rcu_blocking_is_gp(void) { - static DEFINE_RATELIMIT_STATE(rs, 10 * HZ, 1); - - __get_cpu_var(rcu_dyntick_sched).dynticks++; - smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ - WARN_ON_RATELIMIT(!(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1), - &rs); + return num_online_cpus() == 1 && !rcu_scheduler_active; } -#else /* CONFIG_NO_HZ */ -#define rcu_enter_nohz() do { } while (0) -#define rcu_exit_nohz() do { } while (0) -#endif /* CONFIG_NO_HZ */ - #endif /* __LINUX_RCUPREEMPT_H */ |