diff options
Diffstat (limited to 'kernel/rcutiny_plugin.h')
| -rw-r--r-- | kernel/rcutiny_plugin.h | 164 |
1 files changed, 115 insertions, 49 deletions
diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h index f259c676195..9cb1ae4aabd 100644 --- a/kernel/rcutiny_plugin.h +++ b/kernel/rcutiny_plugin.h @@ -23,32 +23,30 @@ */ #include <linux/kthread.h> +#include <linux/module.h> #include <linux/debugfs.h> #include <linux/seq_file.h> -#ifdef CONFIG_RCU_TRACE -#define RCU_TRACE(stmt) stmt -#else /* #ifdef CONFIG_RCU_TRACE */ -#define RCU_TRACE(stmt) -#endif /* #else #ifdef CONFIG_RCU_TRACE */ - /* Global control variables for rcupdate callback mechanism. */ struct rcu_ctrlblk { struct rcu_head *rcucblist; /* List of pending callbacks (CBs). */ struct rcu_head **donetail; /* ->next pointer of last "done" CB. */ struct rcu_head **curtail; /* ->next pointer of last CB. */ RCU_TRACE(long qlen); /* Number of pending CBs. */ + RCU_TRACE(char *name); /* Name of RCU type. */ }; /* Definition for rcupdate control block. */ static struct rcu_ctrlblk rcu_sched_ctrlblk = { .donetail = &rcu_sched_ctrlblk.rcucblist, .curtail = &rcu_sched_ctrlblk.rcucblist, + RCU_TRACE(.name = "rcu_sched") }; static struct rcu_ctrlblk rcu_bh_ctrlblk = { .donetail = &rcu_bh_ctrlblk.rcucblist, .curtail = &rcu_bh_ctrlblk.rcucblist, + RCU_TRACE(.name = "rcu_bh") }; #ifdef CONFIG_DEBUG_LOCK_ALLOC @@ -131,6 +129,7 @@ static struct rcu_preempt_ctrlblk rcu_preempt_ctrlblk = { .rcb.curtail = &rcu_preempt_ctrlblk.rcb.rcucblist, .nexttail = &rcu_preempt_ctrlblk.rcb.rcucblist, .blkd_tasks = LIST_HEAD_INIT(rcu_preempt_ctrlblk.blkd_tasks), + RCU_TRACE(.rcb.name = "rcu_preempt") }; static int rcu_preempted_readers_exp(void); @@ -247,6 +246,13 @@ 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. @@ -306,8 +312,8 @@ static int rcu_boost(void) rt_mutex_lock(&mtx); rt_mutex_unlock(&mtx); /* Keep lockdep happy. */ - return rcu_preempt_ctrlblk.boost_tasks != NULL || - rcu_preempt_ctrlblk.exp_tasks != NULL; + return ACCESS_ONCE(rcu_preempt_ctrlblk.boost_tasks) != NULL || + ACCESS_ONCE(rcu_preempt_ctrlblk.exp_tasks) != NULL; } /* @@ -334,7 +340,7 @@ 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; @@ -353,14 +359,6 @@ 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. @@ -427,7 +425,7 @@ 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(); } /* @@ -648,7 +646,7 @@ 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()) @@ -674,7 +672,7 @@ 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); } /* @@ -697,20 +695,6 @@ void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) } EXPORT_SYMBOL_GPL(call_rcu); -void rcu_barrier(void) -{ - struct rcu_synchronize rcu; - - init_rcu_head_on_stack(&rcu.head); - init_completion(&rcu.completion); - /* Will wake me after RCU finished. */ - call_rcu(&rcu.head, wakeme_after_rcu); - /* Wait for it. */ - wait_for_completion(&rcu.completion); - destroy_rcu_head_on_stack(&rcu.head); -} -EXPORT_SYMBOL_GPL(rcu_barrier); - /* * synchronize_rcu - wait until a grace period has elapsed. * @@ -864,15 +848,6 @@ 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. */ @@ -898,6 +873,103 @@ 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); +} + +#ifdef CONFIG_RCU_TRACE + +/* + * Is the current CPU running the RCU-callbacks kthread? + * Caller must have preemption disabled. + */ +static bool rcu_is_callbacks_kthread(void) +{ + return rcu_kthread_task == current; +} + +#endif /* #ifdef CONFIG_RCU_TRACE */ + +/* + * 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); +} + +#ifdef CONFIG_RCU_TRACE + +/* + * There is no callback kthread, so this thread is never it. + */ +static bool rcu_is_callbacks_kthread(void) +{ + return false; +} + +#endif /* #ifdef CONFIG_RCU_TRACE */ + +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> @@ -913,12 +985,6 @@ 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 |