diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcutiny.c | 71 | ||||
| -rw-r--r-- | kernel/rcutiny_plugin.h | 15 |
2 files changed, 66 insertions, 20 deletions
diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c index d806735342a..86eef29cdfb 100644 --- a/kernel/rcutiny.c +++ b/kernel/rcutiny.c @@ -59,8 +59,15 @@ int rcu_scheduler_active __read_mostly; EXPORT_SYMBOL_GPL(rcu_scheduler_active); #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ +/* Controls for rcu_cbs() kthread, replacing RCU_SOFTIRQ used previously. */ +static struct task_struct *rcu_cbs_task; +static DECLARE_WAIT_QUEUE_HEAD(rcu_cbs_wq); +static unsigned long have_rcu_cbs; +static void invoke_rcu_cbs(void); + /* Forward declarations for rcutiny_plugin.h. */ -static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp); +static void rcu_process_callbacks(struct rcu_ctrlblk *rcp); +static int rcu_cbs(void *arg); static void __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), struct rcu_ctrlblk *rcp); @@ -123,7 +130,7 @@ void rcu_sched_qs(int cpu) { if (rcu_qsctr_help(&rcu_sched_ctrlblk) + rcu_qsctr_help(&rcu_bh_ctrlblk)) - raise_softirq(RCU_SOFTIRQ); + invoke_rcu_cbs(); } /* @@ -132,7 +139,7 @@ void rcu_sched_qs(int cpu) void rcu_bh_qs(int cpu) { if (rcu_qsctr_help(&rcu_bh_ctrlblk)) - raise_softirq(RCU_SOFTIRQ); + invoke_rcu_cbs(); } /* @@ -152,10 +159,10 @@ void rcu_check_callbacks(int cpu, int user) } /* - * Helper function for rcu_process_callbacks() that operates on the - * specified rcu_ctrlkblk structure. + * Invoke the RCU callbacks on the specified rcu_ctrlkblk structure + * whose grace period has elapsed. */ -static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp) +static void rcu_process_callbacks(struct rcu_ctrlblk *rcp) { struct rcu_head *next, *list; unsigned long flags; @@ -180,19 +187,52 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp) next = list->next; prefetch(next); debug_rcu_head_unqueue(list); + local_bh_disable(); list->func(list); + local_bh_enable(); list = next; } } /* - * Invoke any callbacks whose grace period has completed. + * This kthread invokes RCU callbacks whose grace periods have + * elapsed. It is awakened as needed, and takes the place of the + * RCU_SOFTIRQ that was used previously for this purpose. + * This is a kthread, but it is never stopped, at least not until + * the system goes down. + */ +static int rcu_cbs(void *arg) +{ + unsigned long work; + unsigned long flags; + + for (;;) { + wait_event(rcu_cbs_wq, have_rcu_cbs != 0); + local_irq_save(flags); + work = have_rcu_cbs; + have_rcu_cbs = 0; + local_irq_restore(flags); + if (work) { + rcu_process_callbacks(&rcu_sched_ctrlblk); + rcu_process_callbacks(&rcu_bh_ctrlblk); + rcu_preempt_process_callbacks(); + } + } + + return 0; /* Not reached, but needed to shut gcc up. */ +} + +/* + * Wake up rcu_cbs() to process callbacks now eligible for invocation. */ -static void rcu_process_callbacks(struct softirq_action *unused) +static void invoke_rcu_cbs(void) { - __rcu_process_callbacks(&rcu_sched_ctrlblk); - __rcu_process_callbacks(&rcu_bh_ctrlblk); - rcu_preempt_process_callbacks(); + unsigned long flags; + + local_irq_save(flags); + have_rcu_cbs = 1; + wake_up(&rcu_cbs_wq); + local_irq_restore(flags); } /* @@ -282,7 +322,12 @@ void rcu_barrier_sched(void) } EXPORT_SYMBOL_GPL(rcu_barrier_sched); -void __init rcu_init(void) +/* + * Spawn the kthread that invokes RCU callbacks. + */ +static int __init rcu_spawn_kthreads(void) { - open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); + rcu_cbs_task = kthread_run(rcu_cbs, NULL, "rcu_cbs"); + return 0; } +early_initcall(rcu_spawn_kthreads); diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h index 6ceca4f745f..95f9239df51 100644 --- a/kernel/rcutiny_plugin.h +++ b/kernel/rcutiny_plugin.h @@ -22,6 +22,8 @@ * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> */ +#include <linux/kthread.h> + #ifdef CONFIG_TINY_PREEMPT_RCU #include <linux/delay.h> @@ -164,9 +166,9 @@ static void rcu_preempt_cpu_qs(void) if (!rcu_preempt_blocked_readers_any()) rcu_preempt_ctrlblk.rcb.donetail = rcu_preempt_ctrlblk.nexttail; - /* If there are done callbacks, make RCU_SOFTIRQ process them. */ + /* If there are done callbacks, cause them to be invoked. */ if (*rcu_preempt_ctrlblk.rcb.donetail != NULL) - raise_softirq(RCU_SOFTIRQ); + invoke_rcu_cbs(); } /* @@ -374,7 +376,7 @@ static void rcu_preempt_check_callbacks(void) rcu_preempt_cpu_qs(); if (&rcu_preempt_ctrlblk.rcb.rcucblist != rcu_preempt_ctrlblk.rcb.donetail) - raise_softirq(RCU_SOFTIRQ); + invoke_rcu_cbs(); if (rcu_preempt_gp_in_progress() && rcu_cpu_blocking_cur_gp() && rcu_preempt_running_reader()) @@ -383,7 +385,7 @@ static void rcu_preempt_check_callbacks(void) /* * TINY_PREEMPT_RCU has an extra callback-list tail pointer to - * update, so this is invoked from __rcu_process_callbacks() to + * update, so this is invoked from rcu_process_callbacks() to * handle that case. Of course, it is invoked for all flavors of * RCU, but RCU callbacks can appear only on one of the lists, and * neither ->nexttail nor ->donetail can possibly be NULL, so there @@ -400,7 +402,7 @@ static void rcu_preempt_remove_callbacks(struct rcu_ctrlblk *rcp) */ static void rcu_preempt_process_callbacks(void) { - __rcu_process_callbacks(&rcu_preempt_ctrlblk.rcb); + rcu_process_callbacks(&rcu_preempt_ctrlblk.rcb); } /* @@ -599,14 +601,13 @@ static void rcu_preempt_process_callbacks(void) #endif /* #else #ifdef CONFIG_TINY_PREEMPT_RCU */ #ifdef CONFIG_DEBUG_LOCK_ALLOC - #include <linux/kernel_stat.h> /* * During boot, we forgive RCU lockdep issues. After this function is * invoked, we start taking RCU lockdep issues seriously. */ -void rcu_scheduler_starting(void) +void __init rcu_scheduler_starting(void) { WARN_ON(nr_context_switches() > 0); rcu_scheduler_active = 1; |