diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcutiny.c | 74 | ||||
| -rw-r--r-- | kernel/rcutiny_plugin.h | 110 |
2 files changed, 93 insertions, 91 deletions
diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c index 1c37bdd464f..c9321d86999 100644 --- a/kernel/rcutiny.c +++ b/kernel/rcutiny.c @@ -43,16 +43,11 @@ #include "rcu.h" -/* Controls for rcu_kthread() kthread, replacing RCU_SOFTIRQ used previously. */ -static struct task_struct *rcu_kthread_task; -static DECLARE_WAIT_QUEUE_HEAD(rcu_kthread_wq); -static unsigned long have_rcu_kthread_work; - /* Forward declarations for rcutiny_plugin.h. */ struct rcu_ctrlblk; -static void invoke_rcu_kthread(void); -static void rcu_process_callbacks(struct rcu_ctrlblk *rcp); -static int rcu_kthread(void *arg); +static void invoke_rcu_callbacks(void); +static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp); +static void rcu_process_callbacks(struct softirq_action *unused); static void __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), struct rcu_ctrlblk *rcp); @@ -102,16 +97,6 @@ static int rcu_qsctr_help(struct rcu_ctrlblk *rcp) } /* - * Wake up rcu_kthread() to process callbacks now eligible for invocation - * or to boost readers. - */ -static void invoke_rcu_kthread(void) -{ - have_rcu_kthread_work = 1; - wake_up(&rcu_kthread_wq); -} - -/* * Record an rcu quiescent state. And an rcu_bh quiescent state while we * are at it, given that any rcu quiescent state is also an rcu_bh * quiescent state. Use "+" instead of "||" to defeat short circuiting. @@ -123,7 +108,7 @@ void rcu_sched_qs(int cpu) local_irq_save(flags); if (rcu_qsctr_help(&rcu_sched_ctrlblk) + rcu_qsctr_help(&rcu_bh_ctrlblk)) - invoke_rcu_kthread(); + invoke_rcu_callbacks(); local_irq_restore(flags); } @@ -136,7 +121,7 @@ void rcu_bh_qs(int cpu) local_irq_save(flags); if (rcu_qsctr_help(&rcu_bh_ctrlblk)) - invoke_rcu_kthread(); + invoke_rcu_callbacks(); local_irq_restore(flags); } @@ -160,7 +145,7 @@ void rcu_check_callbacks(int cpu, int user) * 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; @@ -200,36 +185,11 @@ static void rcu_process_callbacks(struct rcu_ctrlblk *rcp) RCU_TRACE(trace_rcu_batch_end(rcp->name, cb_count)); } -/* - * 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_kthread(void *arg) +static void rcu_process_callbacks(struct softirq_action *unused) { - unsigned long work; - unsigned long morework; - unsigned long flags; - - for (;;) { - wait_event_interruptible(rcu_kthread_wq, - have_rcu_kthread_work != 0); - morework = rcu_boost(); - local_irq_save(flags); - work = have_rcu_kthread_work; - have_rcu_kthread_work = morework; - local_irq_restore(flags); - if (work) { - rcu_process_callbacks(&rcu_sched_ctrlblk); - rcu_process_callbacks(&rcu_bh_ctrlblk); - rcu_preempt_process_callbacks(); - } - schedule_timeout_interruptible(1); /* Leave CPU for others. */ - } - - return 0; /* Not reached, but needed to shut gcc up. */ + __rcu_process_callbacks(&rcu_sched_ctrlblk); + __rcu_process_callbacks(&rcu_bh_ctrlblk); + rcu_preempt_process_callbacks(); } /* @@ -291,17 +251,3 @@ void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) __call_rcu(head, func, &rcu_bh_ctrlblk); } EXPORT_SYMBOL_GPL(call_rcu_bh); - -/* - * Spawn the kthread that invokes RCU callbacks. - */ -static int __init rcu_spawn_kthreads(void) -{ - struct sched_param sp; - - rcu_kthread_task = kthread_run(rcu_kthread, NULL, "rcu_kthread"); - sp.sched_priority = RCU_BOOST_PRIO; - sched_setscheduler_nocheck(rcu_kthread_task, SCHED_FIFO, &sp); - return 0; -} -early_initcall(rcu_spawn_kthreads); diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h index 791ddf7c99a..02aa7139861 100644 --- a/kernel/rcutiny_plugin.h +++ b/kernel/rcutiny_plugin.h @@ -245,6 +245,13 @@ static void show_tiny_preempt_stats(struct seq_file *m) #include "rtmutex_common.h" +#define RCU_BOOST_PRIO CONFIG_RCU_BOOST_PRIO + +/* Controls for rcu_kthread() kthread. */ +static struct task_struct *rcu_kthread_task; +static DECLARE_WAIT_QUEUE_HEAD(rcu_kthread_wq); +static unsigned long have_rcu_kthread_work; + /* * Carry out RCU priority boosting on the task indicated by ->boost_tasks, * and advance ->boost_tasks to the next task in the ->blkd_tasks list. @@ -332,7 +339,7 @@ static int rcu_initiate_boost(void) if (rcu_preempt_ctrlblk.exp_tasks == NULL) rcu_preempt_ctrlblk.boost_tasks = rcu_preempt_ctrlblk.gp_tasks; - invoke_rcu_kthread(); + invoke_rcu_callbacks(); } else RCU_TRACE(rcu_initiate_boost_trace()); return 1; @@ -351,14 +358,6 @@ static void rcu_preempt_boost_start_gp(void) #else /* #ifdef CONFIG_RCU_BOOST */ /* - * If there is no RCU priority boosting, we don't boost. - */ -static int rcu_boost(void) -{ - return 0; -} - -/* * If there is no RCU priority boosting, we don't initiate boosting, * but we do indicate whether there are blocked readers blocking the * current grace period. @@ -425,7 +424,7 @@ static void rcu_preempt_cpu_qs(void) /* If there are done callbacks, cause them to be invoked. */ if (*rcu_preempt_ctrlblk.rcb.donetail != NULL) - invoke_rcu_kthread(); + invoke_rcu_callbacks(); } /* @@ -646,7 +645,7 @@ static void rcu_preempt_check_callbacks(void) rcu_preempt_cpu_qs(); if (&rcu_preempt_ctrlblk.rcb.rcucblist != rcu_preempt_ctrlblk.rcb.donetail) - invoke_rcu_kthread(); + invoke_rcu_callbacks(); if (rcu_preempt_gp_in_progress() && rcu_cpu_blocking_cur_gp() && rcu_preempt_running_reader()) @@ -672,7 +671,7 @@ 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); } /* @@ -848,15 +847,6 @@ static void show_tiny_preempt_stats(struct seq_file *m) #endif /* #ifdef CONFIG_RCU_TRACE */ /* - * Because preemptible RCU does not exist, it is never necessary to - * boost preempted RCU readers. - */ -static int rcu_boost(void) -{ - return 0; -} - -/* * Because preemptible RCU does not exist, it never has any callbacks * to check. */ @@ -882,6 +872,78 @@ static void rcu_preempt_process_callbacks(void) #endif /* #else #ifdef CONFIG_TINY_PREEMPT_RCU */ +#ifdef CONFIG_RCU_BOOST + +/* + * Wake up rcu_kthread() to process callbacks now eligible for invocation + * or to boost readers. + */ +static void invoke_rcu_callbacks(void) +{ + have_rcu_kthread_work = 1; + wake_up(&rcu_kthread_wq); +} + +/* + * This kthread invokes RCU callbacks whose grace periods have + * elapsed. It is awakened as needed, and takes the place of the + * RCU_SOFTIRQ that is used for this purpose when boosting is disabled. + * This is a kthread, but it is never stopped, at least not until + * the system goes down. + */ +static int rcu_kthread(void *arg) +{ + unsigned long work; + unsigned long morework; + unsigned long flags; + + for (;;) { + wait_event_interruptible(rcu_kthread_wq, + have_rcu_kthread_work != 0); + morework = rcu_boost(); + local_irq_save(flags); + work = have_rcu_kthread_work; + have_rcu_kthread_work = morework; + local_irq_restore(flags); + if (work) + rcu_process_callbacks(NULL); + schedule_timeout_interruptible(1); /* Leave CPU for others. */ + } + + return 0; /* Not reached, but needed to shut gcc up. */ +} + +/* + * Spawn the kthread that invokes RCU callbacks. + */ +static int __init rcu_spawn_kthreads(void) +{ + struct sched_param sp; + + rcu_kthread_task = kthread_run(rcu_kthread, NULL, "rcu_kthread"); + sp.sched_priority = RCU_BOOST_PRIO; + sched_setscheduler_nocheck(rcu_kthread_task, SCHED_FIFO, &sp); + return 0; +} +early_initcall(rcu_spawn_kthreads); + +#else /* #ifdef CONFIG_RCU_BOOST */ + +/* + * Start up softirq processing of callbacks. + */ +void invoke_rcu_callbacks(void) +{ + raise_softirq(RCU_SOFTIRQ); +} + +void rcu_init(void) +{ + open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); +} + +#endif /* #else #ifdef CONFIG_RCU_BOOST */ + #ifdef CONFIG_DEBUG_LOCK_ALLOC #include <linux/kernel_stat.h> @@ -897,12 +959,6 @@ void __init rcu_scheduler_starting(void) #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ -#ifdef CONFIG_RCU_BOOST -#define RCU_BOOST_PRIO CONFIG_RCU_BOOST_PRIO -#else /* #ifdef CONFIG_RCU_BOOST */ -#define RCU_BOOST_PRIO 1 -#endif /* #else #ifdef CONFIG_RCU_BOOST */ - #ifdef CONFIG_RCU_TRACE #ifdef CONFIG_RCU_BOOST |