diff options
| -rw-r--r-- | include/linux/futex.h | 4 | ||||
| -rw-r--r-- | include/linux/rcupdate.h | 18 | ||||
| -rw-r--r-- | include/linux/rcutree.h | 13 | ||||
| -rw-r--r-- | init/main.c | 1 | ||||
| -rw-r--r-- | kernel/exit.c | 2 | ||||
| -rw-r--r-- | kernel/fork.c | 10 | ||||
| -rw-r--r-- | kernel/futex.c | 3 | ||||
| -rw-r--r-- | kernel/panic.c | 3 | ||||
| -rw-r--r-- | kernel/rcupdate.c | 140 | ||||
| -rw-r--r-- | kernel/rcutorture.c | 4 | ||||
| -rw-r--r-- | kernel/rcutree.c | 330 | ||||
| -rw-r--r-- | kernel/rcutree.h | 86 | ||||
| -rw-r--r-- | kernel/rcutree_plugin.h | 103 | ||||
| -rw-r--r-- | kernel/rcutree_trace.c | 4 |
14 files changed, 405 insertions, 316 deletions
diff --git a/include/linux/futex.h b/include/linux/futex.h index 8ec17997d94f..1e5a26d79232 100644 --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -33,8 +33,8 @@ #define FUTEX_LOCK_PI_PRIVATE (FUTEX_LOCK_PI | FUTEX_PRIVATE_FLAG) #define FUTEX_UNLOCK_PI_PRIVATE (FUTEX_UNLOCK_PI | FUTEX_PRIVATE_FLAG) #define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI | FUTEX_PRIVATE_FLAG) -#define FUTEX_WAIT_BITSET_PRIVATE (FUTEX_WAIT_BITS | FUTEX_PRIVATE_FLAG) -#define FUTEX_WAKE_BITSET_PRIVATE (FUTEX_WAKE_BITS | FUTEX_PRIVATE_FLAG) +#define FUTEX_WAIT_BITSET_PRIVATE (FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG) +#define FUTEX_WAKE_BITSET_PRIVATE (FUTEX_WAKE_BITSET | FUTEX_PRIVATE_FLAG) #define FUTEX_WAIT_REQUEUE_PI_PRIVATE (FUTEX_WAIT_REQUEUE_PI | \ FUTEX_PRIVATE_FLAG) #define FUTEX_CMP_REQUEUE_PI_PRIVATE (FUTEX_CMP_REQUEUE_PI | \ diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 6fe0363724e9..3ebd0b7bcb08 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -77,7 +77,7 @@ extern int rcu_scheduler_active; #error "Unknown RCU implementation specified to kernel configuration" #endif -#define RCU_HEAD_INIT { .next = NULL, .func = NULL } +#define RCU_HEAD_INIT { .next = NULL, .func = NULL } #define RCU_HEAD(head) struct rcu_head head = RCU_HEAD_INIT #define INIT_RCU_HEAD(ptr) do { \ (ptr)->next = NULL; (ptr)->func = NULL; \ @@ -129,12 +129,6 @@ static inline void rcu_read_lock(void) rcu_read_acquire(); } -/** - * rcu_read_unlock - marks the end of an RCU read-side critical section. - * - * See rcu_read_lock() for more information. - */ - /* * So where is rcu_write_lock()? It does not exist, as there is no * way for writers to lock out RCU readers. This is a feature, not @@ -144,6 +138,12 @@ static inline void rcu_read_lock(void) * used as well. RCU does not care how the writers keep out of each * others' way, as long as they do so. */ + +/** + * rcu_read_unlock - marks the end of an RCU read-side critical section. + * + * See rcu_read_lock() for more information. + */ static inline void rcu_read_unlock(void) { rcu_read_release(); @@ -196,6 +196,8 @@ static inline void rcu_read_lock_sched(void) __acquire(RCU_SCHED); rcu_read_acquire(); } + +/* Used by lockdep and tracing: cannot be traced, cannot call lockdep. */ static inline notrace void rcu_read_lock_sched_notrace(void) { preempt_disable_notrace(); @@ -213,6 +215,8 @@ static inline void rcu_read_unlock_sched(void) __release(RCU_SCHED); preempt_enable(); } + +/* Used by lockdep and tracing: cannot be traced, cannot call lockdep. */ static inline notrace void rcu_read_unlock_sched_notrace(void) { __release(RCU_SCHED); diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 37682770e9d2..46e9ab3ee6e1 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -30,10 +30,14 @@ #ifndef __LINUX_RCUTREE_H #define __LINUX_RCUTREE_H +struct notifier_block; + extern void rcu_sched_qs(int cpu); extern void rcu_bh_qs(int cpu); - +extern int rcu_cpu_notify(struct notifier_block *self, + unsigned long action, void *hcpu); extern int rcu_needs_cpu(int cpu); +extern int rcu_expedited_torture_stats(char *page); #ifdef CONFIG_TREE_PREEMPT_RCU @@ -85,16 +89,11 @@ static inline void synchronize_rcu_bh_expedited(void) extern void __rcu_init(void); extern void rcu_check_callbacks(int cpu, int user); -extern void rcu_restart_cpu(int cpu); extern long rcu_batches_completed(void); extern long rcu_batches_completed_bh(void); extern long rcu_batches_completed_sched(void); -static inline void rcu_init_sched(void) -{ -} - #ifdef CONFIG_NO_HZ void rcu_enter_nohz(void); void rcu_exit_nohz(void); @@ -107,7 +106,7 @@ static inline void rcu_exit_nohz(void) } #endif /* CONFIG_NO_HZ */ -/* A context switch is a grace period for rcutree. */ +/* A context switch is a grace period for RCU-sched and RCU-bh. */ static inline int rcu_blocking_is_gp(void) { return num_online_cpus() == 1; diff --git a/init/main.c b/init/main.c index 7449819a4805..5988debfc505 100644 --- a/init/main.c +++ b/init/main.c @@ -778,7 +778,6 @@ static void __init do_initcalls(void) */ static void __init do_basic_setup(void) { - rcu_init_sched(); /* needed by module_init stage. */ init_workqueues(); cpuset_init_smp(); usermodehelper_init(); diff --git a/kernel/exit.c b/kernel/exit.c index 5859f598c951..e61891f80123 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -991,8 +991,6 @@ NORET_TYPE void do_exit(long code) tsk->mempolicy = NULL; #endif #ifdef CONFIG_FUTEX - if (unlikely(!list_empty(&tsk->pi_state_list))) - exit_pi_state_list(tsk); if (unlikely(current->pi_state_cache)) kfree(current->pi_state_cache); #endif diff --git a/kernel/fork.c b/kernel/fork.c index 266c6af6ef1b..4c20fff8c13a 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -570,12 +570,18 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm) /* Get rid of any futexes when releasing the mm */ #ifdef CONFIG_FUTEX - if (unlikely(tsk->robust_list)) + if (unlikely(tsk->robust_list)) { exit_robust_list(tsk); + tsk->robust_list = NULL; + } #ifdef CONFIG_COMPAT - if (unlikely(tsk->compat_robust_list)) + if (unlikely(tsk->compat_robust_list)) { compat_exit_robust_list(tsk); + tsk->compat_robust_list = NULL; + } #endif + if (unlikely(!list_empty(&tsk->pi_state_list))) + exit_pi_state_list(tsk); #endif /* Get rid of any cached register state */ diff --git a/kernel/futex.c b/kernel/futex.c index b911adceb2c4..4949d336d88d 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -916,8 +916,8 @@ retry: hb1 = hash_futex(&key1); hb2 = hash_futex(&key2); - double_lock_hb(hb1, hb2); retry_private: + double_lock_hb(hb1, hb2); op_ret = futex_atomic_op_inuser(op, uaddr2); if (unlikely(op_ret < 0)) { @@ -2117,7 +2117,6 @@ int handle_early_requeue_pi_wakeup(struct futex_hash_bucket *hb, * Unqueue the futex_q and determine which it was. */ plist_del(&q->list, &q->list.plist); - drop_futex_key_refs(&q->key); if (timeout && !timeout->task) ret = -ETIMEDOUT; diff --git a/kernel/panic.c b/kernel/panic.c index bcdef26e3332..96b45d0b4ba5 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -90,6 +90,8 @@ NORET_TYPE void panic(const char * fmt, ...) atomic_notifier_call_chain(&panic_notifier_list, 0, buf); + bust_spinlocks(0); + if (!panic_blink) panic_blink = no_blink; @@ -136,7 +138,6 @@ NORET_TYPE void panic(const char * fmt, ...) mdelay(1); i++; } - bust_spinlocks(0); } EXPORT_SYMBOL(panic); diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index 37ac45483082..400183346ad2 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -46,22 +46,15 @@ #include <linux/module.h> #include <linux/kernel_stat.h> -enum rcu_barrier { - RCU_BARRIER_STD, - RCU_BARRIER_BH, - RCU_BARRIER_SCHED, -}; +#ifdef CONFIG_DEBUG_LOCK_ALLOC +static struct lock_class_key rcu_lock_key; +struct lockdep_map rcu_lock_map = + STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key); +EXPORT_SYMBOL_GPL(rcu_lock_map); +#endif -static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL}; -static atomic_t rcu_barrier_cpu_count; -static DEFINE_MUTEX(rcu_barrier_mutex); -static struct completion rcu_barrier_completion; int rcu_scheduler_active __read_mostly; -static atomic_t rcu_migrate_type_count = ATOMIC_INIT(0); -static struct rcu_head rcu_migrate_head[3]; -static DECLARE_WAIT_QUEUE_HEAD(rcu_migrate_wq); - /* * Awaken the corresponding synchronize_rcu() instance now that a * grace period has elapsed. @@ -164,129 +157,10 @@ void synchronize_rcu_bh(void) } EXPORT_SYMBOL_GPL(synchronize_rcu_bh); -static void rcu_barrier_callback(struct rcu_head *notused) -{ - if (atomic_dec_and_test(&rcu_barrier_cpu_count)) - complete(&rcu_barrier_completion); -} - -/* - * Called with preemption disabled, and from cross-cpu IRQ context. - */ -static void rcu_barrier_func(void *type) -{ - int cpu = smp_processor_id(); - struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu); - - atomic_inc(&rcu_barrier_cpu_count); - switch ((enum rcu_barrier)type) { - case RCU_BARRIER_STD: - call_rcu(head, rcu_barrier_callback); - break; - case RCU_BARRIER_BH: - call_rcu_bh(head, rcu_barrier_callback); - break; - case RCU_BARRIER_SCHED: - call_rcu_sched(head, rcu_barrier_callback); - break; - } -} - -static inline void wait_migrated_callbacks(void) -{ - wait_event(rcu_migrate_wq, !atomic_read(&rcu_migrate_type_count)); - smp_mb(); /* In case we didn't sleep. */ -} - -/* - * Orchestrate the specified type of RCU barrier, waiting for all - * RCU callbacks of the specified type to complete. - */ -static void _rcu_barrier(enum rcu_barrier type) -{ - BUG_ON(in_interrupt()); - /* Take cpucontrol mutex to protect against CPU hotplug */ - mutex_lock(&rcu_barrier_mutex); - init_completion(&rcu_barrier_completion); - /* - * Initialize rcu_barrier_cpu_count to 1, then invoke - * rcu_barrier_func() on each CPU, so that each CPU also has - * incremented rcu_barrier_cpu_count. Only then is it safe to - * decrement rcu_barrier_cpu_count -- otherwise the first CPU - * might complete its grace period before all of the other CPUs - * did their increment, causing this function to return too - * early. - */ - atomic_set(&rcu_barrier_cpu_count, 1); - on_each_cpu(rcu_barrier_func, (void *)type, 1); - if (atomic_dec_and_test(&rcu_barrier_cpu_count)) - complete(&rcu_barrier_completion); - wait_for_completion(&rcu_barrier_completion); - mutex_unlock(&rcu_barrier_mutex); - wait_migrated_callbacks(); -} - -/** - * rcu_barrier - Wait until all in-flight call_rcu() callbacks complete. - */ -void rcu_barrier(void) -{ - _rcu_barrier(RCU_BARRIER_STD); -} -EXPORT_SYMBOL_GPL(rcu_barrier); - -/** - * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete. - */ -void rcu_barrier_bh(void) -{ - _rcu_barrier(RCU_BARRIER_BH); -} -EXPORT_SYMBOL_GPL(rcu_barrier_bh); - -/** - * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks. - */ -void rcu_barrier_sched(void) -{ - _rcu_barrier(RCU_BARRIER_SCHED); -} -EXPORT_SYMBOL_GPL(rcu_barrier_sched); - -static void rcu_migrate_callback(struct rcu_head *notused) -{ - if (atomic_dec_and_test(&rcu_migrate_type_count)) - wake_up(&rcu_migrate_wq); -} - -extern int rcu_cpu_notify(struct notifier_block *self, - unsigned long action, void *hcpu); - static int __cpuinit rcu_barrier_cpu_hotplug(struct notifier_block *self, unsigned long action, void *hcpu) { - rcu_cpu_notify(self, action, hcpu); - if (action == CPU_DYING) { - /* - * preempt_disable() in on_each_cpu() prevents stop_machine(), - * so when "on_each_cpu(rcu_barrier_func, (void *)type, 1);" - * returns, all online cpus have queued rcu_barrier_func(), - * and the dead cpu(if it exist) queues rcu_migrate_callback()s. - * - * These callbacks ensure _rcu_barrier() waits for all - * RCU callbacks of the specified type to complete. - */ - atomic_set(&rcu_migrate_type_count, 3); - call_rcu_bh(rcu_migrate_head, rcu_migrate_callback); - call_rcu_sched(rcu_migrate_head + 1, rcu_migrate_callback); - call_rcu(rcu_migrate_head + 2, rcu_migrate_callback); - } else if (action == CPU_DOWN_PREPARE) { - /* Don't need to wait until next removal operation. */ - /* rcu_migrate_head is protected by cpu_add_remove_lock */ - wait_migrated_callbacks(); - } - - return NOTIFY_OK; + return rcu_cpu_notify(self, action, hcpu); } void __init rcu_init(void) diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index 233768f21f97..697c0a0229d4 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -606,8 +606,6 @@ static struct rcu_torture_ops sched_ops_sync = { .name = "sched_sync" }; -extern int rcu_expedited_torture_stats(char *page); - static struct rcu_torture_ops sched_expedited_ops = { .init = rcu_sync_torture_init, .cleanup = NULL, @@ -650,7 +648,7 @@ rcu_torture_writer(void *arg) old_rp = rcu_torture_current; rp->rtort_mbtest = 1; rcu_assign_pointer(rcu_torture_current, rp); - smp_wmb(); + smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */ if (old_rp) { i = old_rp->rtort_pipe_count; if (i > RCU_TORTURE_PIPE_LEN) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 52b06f6e158c..705f02ac7433 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -49,13 +49,6 @@ #include "rcutree.h" -#ifdef CONFIG_DEBUG_LOCK_ALLOC -static struct lock_class_key rcu_lock_key; -struct lockdep_map rcu_lock_map = - STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key); -EXPORT_SYMBOL_GPL(rcu_lock_map); -#endif - /* Data structures. */ #define RCU_STATE_INITIALIZER(name) { \ @@ -70,6 +63,9 @@ EXPORT_SYMBOL_GPL(rcu_lock_map); .gpnum = -300, \ .completed = -300, \ .onofflock = __SPIN_LOCK_UNLOCKED(&name.onofflock), \ + .orphan_cbs_list = NULL, \ + .orphan_cbs_tail = &name.orphan_cbs_list, \ + .orphan_qlen = 0, \ .fqslock = __SPIN_LOCK_UNLOCKED(&name.fqslock), \ .n_force_qs = 0, \ .n_force_qs_ngp = 0, \ @@ -81,24 +77,16 @@ DEFINE_PER_CPU(struct rcu_data, rcu_sched_data); struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state); DEFINE_PER_CPU(struct rcu_data, rcu_bh_data); -extern long rcu_batches_completed_sched(void); -static struct rcu_node *rcu_get_root(struct rcu_state *rsp); -static void cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, - struct rcu_node *rnp, unsigned long flags); -static void cpu_quiet_msk_finish(struct rcu_state *rsp, unsigned long flags); -#ifdef CONFIG_HOTPLUG_CPU -static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp); -#endif /* #ifdef CONFIG_HOTPLUG_CPU */ -static void __rcu_process_callbacks(struct rcu_state *rsp, - struct rcu_data *rdp); -static void __call_rcu(struct rcu_head *head, - void (*func)(struct rcu_head *rcu), - struct rcu_state *rsp); -static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp); -static void __cpuinit rcu_init_percpu_data(int cpu, struct rcu_state *rsp, - int preemptable); -#include "rcutree_plugin.h" +/* + * Return true if an RCU grace period is in progress. The ACCESS_ONCE()s + * permit this function to be invoked without holding the root rcu_node + * structure's ->lock, but of course results can be subject to change. + */ +static int rcu_gp_in_progress(struct rcu_state *rsp) +{ + return ACCESS_ONCE(rsp->completed) != ACCESS_ONCE(rsp->gpnum); +} /* * Note a quiescent state. Because we do not need to know @@ -137,6 +125,10 @@ static int blimit = 10; /* Maximum callbacks per softirq. */ static int qhimark = 10000; /* If this many pending, ignore blimit. */ static int qlowmark = 100; /* Once only this many pending, use blimit. */ +module_param(blimit, int, 0); +module_param(qhimark, int, 0); +module_param(qlowmark, int, 0); + static void force_quiescent_state(struct rcu_state *rsp, int relaxed); static int rcu_pending(int cpu); @@ -173,9 +165,7 @@ cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp) static int cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp) { - /* ACCESS_ONCE() because we are accessing outside of lock. */ - return *rdp->nxttail[RCU_DONE_TAIL] && - ACCESS_ONCE(rsp->completed) == ACCESS_ONCE(rsp->gpnum); + return *rdp->nxttail[RCU_DONE_TAIL] && !rcu_gp_in_progress(rsp); } /* @@ -369,7 +359,7 @@ static long dyntick_recall_completed(struct rcu_state *rsp) /* * Snapshot the specified CPU's dynticks counter so that we can later * credit them with an implicit quiescent state. Return 1 if this CPU - * is already in a quiescent state courtesy of dynticks idle mode. + * is in dynticks idle mode, which is an extended quiescent state. */ static int dyntick_save_progress_counter(struct rcu_data *rdp) { @@ -475,30 +465,34 @@ static void print_other_cpu_stall(struct rcu_state *rsp) long delta; unsigned long flags; struct rcu_node *rnp = rcu_get_root(rsp); - struct rcu_node *rnp_cur = rsp->level[NUM_RCU_LVLS - 1]; - struct rcu_node *rnp_end = &rsp->node[NUM_RCU_NODES]; /* Only let one CPU complain about others per time interval. */ spin_lock_irqsave(&rnp->lock, flags); delta = jiffies - rsp->jiffies_stall; - if (delta < RCU_STALL_RAT_DELAY || rsp->gpnum == rsp->completed) { + if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) { spin_unlock_irqrestore(&rnp->lock, flags); return; } rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_RECHECK; + + /* + * Now rat on any tasks that got kicked up to the root rcu_node + * due to CPU offlining. + */ + rcu_print_task_stall(rnp); spin_unlock_irqrestore(&rnp->lock, flags); /* OK, time to rat on our buddy... */ printk(KERN_ERR "INFO: RCU detected CPU stalls:"); - for (; rnp_cur < rnp_end; rnp_cur++) { + rcu_for_each_leaf_node(rsp, rnp) { rcu_print_task_stall(rnp); - if (rnp_cur->qsmask == 0) + if (rnp->qsmask == 0) continue; - for (cpu = 0; cpu <= rnp_cur->grphi - rnp_cur->grplo; cpu++) - if (rnp_cur->qsmask & (1UL << cpu)) - printk(" %d", rnp_cur->grplo + cpu); + for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++) + if (rnp->qsmask & (1UL << cpu)) + printk(" %d", rnp->grplo + cpu); } printk(" (detected by %d, t=%ld jiffies)\n", smp_processor_id(), (long)(jiffies - rsp->gp_start)); @@ -537,8 +531,7 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) /* We haven't checked in, so go dump stack. */ print_cpu_stall(rsp); - } else if (rsp->gpnum != rsp->completed && - delta >= RCU_STALL_RAT_DELAY) { + } else if (rcu_gp_in_progress(rsp) && delta >= RCU_STALL_RAT_DELAY) { /* They had two time units to dump stack, so complain. */ print_other_cpu_stall(rsp); @@ -617,9 +610,15 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags) note_new_gpnum(rsp, rdp); /* - * Because we are first, we know that all our callbacks will - * be covered by this upcoming grace period, even the ones - * that were registered arbitrarily recently. + * Because this CPU just now started the new grace period, we know + * that all of its callbacks will be covered by this upcoming grace + * period, even the ones that were registered arbitrarily recently. + * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL. + * + * Other CPUs cannot be sure exactly when the grace period started. + * Therefore, their recently registered callbacks must pass through + * an additional RCU_NEXT_READY stage, so that they will be handled + * by the next RCU grace period. */ rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; @@ -657,7 +656,7 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags) * one corresponding to this CPU, due to the fact that we have * irqs disabled. */ - for (rnp = &rsp->node[0]; rnp < &rsp->node[NUM_RCU_NODES]; rnp++) { + rcu_for_each_node_breadth_first(rsp, rnp) { spin_lock(&rnp->lock); /* irqs already disabled. */ rcu_preempt_check_blocked_tasks(rnp); rnp->qsmask = rnp->qsmaskinit; @@ -703,9 +702,9 @@ rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp) * hold rnp->lock, as required by rcu_start_gp(), which will release it. */ static void cpu_quiet_msk_finish(struct rcu_state *rsp, unsigned long flags) - __releases(rnp->lock) + __releases(rcu_get_root(rsp)->lock) { - WARN_ON_ONCE(rsp->completed == rsp->gpnum); + WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); rsp->completed = rsp->gpnum; rcu_process_gp_end(rsp, rsp->rda[smp_processor_id()]); rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */ @@ -842,17 +841,63 @@ rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp) #ifdef CONFIG_HOTPLUG_CPU /* + * Move a dying CPU's RCU callbacks to the ->orphan_cbs_list for the + * specified flavor of RCU. The callbacks will be adopted by the next + * _rcu_barrier() invocation or by the CPU_DEAD notifier, whichever + * comes first. Because this is invoked from the CPU_DYING notifier, + * irqs are already disabled. + */ +static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp) +{ + int i; + struct rcu_data *rdp = rsp->rda[smp_processor_id()]; + + if (rdp->nxtlist == NULL) + return; /* irqs disabled, so comparison is stable. */ + spin_lock(&rsp->onofflock); /* irqs already disabled. */ + *rsp->orphan_cbs_tail = rdp->nxtlist; + rsp->orphan_cbs_tail = rdp->nxttail[RCU_NEXT_TAIL]; + rdp->nxtlist = NULL; + for (i = 0; i < RCU_NEXT_SIZE; i++) + rdp->nxttail[i] = &rdp->nxtlist; + rsp->orphan_qlen += rdp->qlen; + rdp->qlen = 0; + spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ +} + +/* + * Adopt previously orphaned RCU callbacks. + */ +static void rcu_adopt_orphan_cbs(struct rcu_state *rsp) +{ + unsigned long flags; + struct rcu_data *rdp; + + spin_lock_irqsave(&rsp->onofflock, flags); + rdp = rsp->rda[smp_processor_id()]; + if (rsp->orphan_cbs_list == NULL) { + spin_unlock_irqrestore(&rsp->onofflock, flags); + return; + } + *rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_cbs_list; + rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_cbs_tail; + rdp->qlen += rsp->orphan_qlen; + rsp->orphan_cbs_list = NULL; + rsp->orphan_cbs_tail = &rsp->orphan_cbs_list; + rsp->orphan_qlen = 0; + spin_unlock_irqrestore(&rsp->onofflock, flags); +} + +/* * Remove the outgoing CPU from the bitmasks in the rcu_node hierarchy * and move all callbacks from the outgoing CPU to the current one. */ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) { - int i; unsigned long flags; long lastcomp; unsigned long mask; struct rcu_data *rdp = rsp->rda[cpu]; - struct rcu_data *rdp_me; struct rcu_node *rnp; /* Exclude any attempts to start a new grace period. */ @@ -875,32 +920,9 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) } while (rnp != NULL); lastcomp = rsp->completed; - spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ + spin_unlock_irqrestore(&rsp->onofflock, flags); - /* - * Move callbacks from the outgoing CPU to the running CPU. - * Note that the outgoing CPU is now quiscent, so it is now - * (uncharacteristically) safe to access its rcu_data structure. - * Note also that we must carefully retain the order of the - * outgoing CPU's callbacks in order for rcu_barrier() to work - * correctly. Finally, note that we start all the callbacks - * afresh, even those that have passed through a grace period - * and are therefore ready to invoke. The theory is that hotplug - * events are rare, and that if they are frequent enough to - * indefinitely delay callbacks, you have far worse things to - * be worrying about. - */ - rdp_me = rsp->rda[smp_processor_id()]; - if (rdp->nxtlist != NULL) { - *rdp_me->nxttail[RCU_NEXT_TAIL] = rdp->nxtlist; - rdp_me->nxttail[RCU_NEXT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; - rdp->nxtlist = NULL; - for (i = 0; i < RCU_NEXT_SIZE; i++) - rdp->nxttail[i] = &rdp->nxtlist; - rdp_me->qlen += rdp->qlen; - rdp->qlen = 0; - } - local_irq_restore(flags); + rcu_adopt_orphan_cbs(rsp); } /* @@ -918,6 +940,14 @@ static void rcu_offline_cpu(int cpu) #else /* #ifdef CONFIG_HOTPLUG_CPU */ +static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp) +{ +} + +static void rcu_adopt_orphan_cbs(struct rcu_state *rsp) +{ +} + static void rcu_offline_cpu(int cpu) { } @@ -1050,33 +1080,32 @@ static int rcu_process_dyntick(struct rcu_state *rsp, long lastcomp, int cpu; unsigned long flags; unsigned long mask; - struct rcu_node *rnp_cur = rsp->level[NUM_RCU_LVLS - 1]; - struct rcu_node *rnp_end = &rsp->node[NUM_RCU_NODES]; + struct rcu_node *rnp; - for (; rnp_cur < rnp_end; rnp_cur++) { + rcu_for_each_leaf_node(rsp, rnp) { mask = 0; - spin_lock_irqsave(&rnp_cur->lock, flags); + spin_lock_irqsave(&rnp->lock, flags); if (rsp->completed != lastcomp) { - spin_unlock_irqrestore(&rnp_cur->lock, flags); + spin_unlock_irqrestore(&rnp->lock, flags); return 1; } - if (rnp_cur->qsmask == 0) { - spin_unlock_irqrestore(&rnp_cur->lock, flags); + if (rnp->qsmask == 0) { + spin_unlock_irqrestore(&rnp->lock, flags); continue; } - cpu = rnp_cur->grplo; + cpu = rnp->grplo; bit = 1; - for (; cpu <= rnp_cur->grphi; cpu++, bit <<= 1) { - if ((rnp_cur->qsmask & bit) != 0 && f(rsp->rda[cpu])) + for (; cpu <= rnp->grphi; cpu++, bit <<= 1) { + if ((rnp->qsmask & bit) != 0 && f(rsp->rda[cpu])) mask |= bit; } if (mask != 0 && rsp->completed == lastcomp) { - /* cpu_quiet_msk() releases rnp_cur->lock. */ - cpu_quiet_msk(mask, rsp, rnp_cur, flags); + /* cpu_quiet_msk() releases rnp->lock. */ + cpu_quiet_msk(mask, rsp, rnp, flags); continue; } - spin_unlock_irqrestore(&rnp_cur->lock, flags); + spin_unlock_irqrestore(&rnp->lock, flags); } return 0; } @@ -1092,7 +1121,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) struct rcu_node *rnp = rcu_get_root(rsp); u8 signaled; - if (ACCESS_ONCE(rsp->completed) == ACCESS_ONCE(rsp->gpnum)) + if (!rcu_gp_in_progress(rsp)) return; /* No grace period in progress, nothing to force. */ if (!spin_trylock_irqsave(&rsp->fqslock, flags)) { rsp->n_force_qs_lh++; /* Inexact, can lose counts. Tough! */ @@ -1251,7 +1280,7 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), rdp->nxttail[RCU_NEXT_TAIL] = &head->next; /* Start a new grace period if one not already started. */ - if (ACCESS_ONCE(rsp->completed) == ACCESS_ONCE(rsp->gpnum)) { + if (!rcu_gp_in_progress(rsp)) { unsigned long nestflag; struct rcu_node *rnp_root = rcu_get_root(rsp); @@ -1331,7 +1360,7 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) } /* Has an RCU GP gone long enough to send resched IPIs &c? */ - if (ACCESS_ONCE(rsp->completed) != ACCESS_ONCE(rsp->gpnum) && + if (rcu_gp_in_progress(rsp) && ((long)(ACCESS_ONCE(rsp->jiffies_force_qs) - jiffies) < 0)) { rdp->n_rp_need_fqs++; return 1; @@ -1368,6 +1397,82 @@ int rcu_needs_cpu(int cpu) rcu_preempt_needs_cpu(cpu); } +static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL}; +static atomic_t rcu_barrier_cpu_count; +static DEFINE_MUTEX(rcu_barrier_mutex); +static struct completion rcu_barrier_completion; + +static void rcu_barrier_callback(struct rcu_head *notused) +{ + if (atomic_dec_and_test(&rcu_barrier_cpu_count)) + complete(&rcu_barrier_completion); +} + +/* + * Called with preemption disabled, and from cross-cpu IRQ context. + */ +static void rcu_barrier_func(void *type) +{ + int cpu = smp_processor_id(); + struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu); + void (*call_rcu_func)(struct rcu_head *head, + void (*func)(struct rcu_head *head)); + + atomic_inc(&rcu_barrier_cpu_count); + call_rcu_func = type; + call_rcu_func(head, rcu_barrier_callback); +} + +/* + * Orchestrate the specified type of RCU barrier, waiting for all + * RCU callbacks of the specified type to complete. + */ +static void _rcu_barrier(struct rcu_state *rsp, + void (*call_rcu_func)(struct rcu_head *head, + void (*func)(struct rcu_head *head))) +{ + BUG_ON(in_interrupt()); + /* Take mutex to serialize concurrent rcu_barrier() requests. */ + mutex_lock(&rcu_barrier_mutex); + init_completion(&rcu_barrier_completion); + /* + * Initialize rcu_barrier_cpu_count to 1, then invoke + * rcu_barrier_func() on each CPU, so that each CPU also has + * incremented rcu_barrier_cpu_count. Only then is it safe to + * decrement rcu_barrier_cpu_count -- otherwise the first CPU + * might complete its grace period before all of the other CPUs + * did their increment, causing this function to return too + * early. + */ + atomic_set(&rcu_barrier_cpu_count, 1); + preempt_disable(); /* stop CPU_DYING from filling orphan_cbs_list */ + rcu_adopt_orphan_cbs(rsp); + on_each_cpu(rcu_barrier_func, (void *)call_rcu_func, 1); + preempt_enable(); /* CPU_DYING can again fill orphan_cbs_list */ + if (atomic_dec_and_test(&rcu_barrier_cpu_count)) + complete(&rcu_barrier_completion); + wait_for_completion(&rcu_barrier_completion); + mutex_unlock(&rcu_barrier_mutex); +} + +/** + * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete. + */ +void rcu_barrier_bh(void) +{ + _rcu_barrier(&rcu_bh_state, call_rcu_bh); +} +EXPORT_SYMBOL_GPL(rcu_barrier_bh); + +/** + * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks. + */ +void rcu_barrier_sched(void) +{ + _rcu_barrier(&rcu_sched_state, call_rcu_sched); +} +EXPORT_SYMBOL_GPL(rcu_barrier_sched); + /* * Do boot-time initialization of a CPU's per-CPU RCU data. */ @@ -1464,6 +1569,22 @@ int __cpuinit rcu_cpu_notify(struct notifier_block *self, case CPU_UP_PREPARE_FROZEN: rcu_online_cpu(cpu); break; + case CPU_DYING: + case CPU_DYING_FROZEN: + /* + * preempt_disable() in _rcu_barrier() prevents stop_machine(), + * so when "on_each_cpu(rcu_barrier_func, (void *)type, 1);" + * returns, all online cpus have queued rcu_barrier_func(). + * The dying CPU clears its cpu_online_mask bit and + * moves all of its RCU callbacks to ->orphan_cbs_list + * in the context of stop_machine(), so subsequent calls + * to _rcu_barrier() will adopt these callbacks and only + * then queue rcu_barrier_func() on all remaining CPUs. + */ + rcu_send_cbs_to_orphanage(&rcu_bh_state); + rcu_send_cbs_to_orphanage(&rcu_sched_state); + rcu_preempt_send_cbs_to_orphanage(); + break; case CPU_DEAD: case CPU_DEAD_FROZEN: case CPU_UP_CANCELED: @@ -1526,7 +1647,8 @@ static void __init rcu_init_one(struct rcu_state *rsp) cpustride *= rsp->levelspread[i]; rnp = rsp->level[i]; for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) { - spin_lock_init(&rnp->lock); + if (rnp != rcu_get_root(rsp)) + spin_lock_init(&rnp->lock); rnp->gpnum = 0; rnp->qsmask = 0; rnp->qsmaskinit = 0; @@ -1549,6 +1671,7 @@ static void __init rcu_init_one(struct rcu_state *rsp) INIT_LIST_HEAD(&rnp->blocked_tasks[1]); } } + spin_lock_init(&rcu_get_root(rsp)->lock); } /* @@ -1558,6 +1681,10 @@ static void __init rcu_init_one(struct rcu_state *rsp) */ #define RCU_INIT_FLAVOR(rsp, rcu_data) \ do { \ + int i; \ + int j; \ + struct rcu_node *rnp; \ + \ rcu_init_one(rsp); \ rnp = (rsp)->level[NUM_RCU_LVLS - 1]; \ j = 0; \ @@ -1570,31 +1697,8 @@ do { \ } \ } while (0) -#ifdef CONFIG_TREE_PREEMPT_RCU - -void __init __rcu_init_preempt(void) -{ - int i; /* All used by RCU_INIT_FLAVOR(). */ - int j; - struct rcu_node *rnp; - - RCU_INIT_FLAVOR(&rcu_preempt_state, rcu_preempt_data); -} - -#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */ - -void __init __rcu_init_preempt(void) -{ -} - -#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */ - void __init __rcu_init(void) { - int i; /* All used by RCU_INIT_FLAVOR(). */ - int j; - struct rcu_node *rnp; - rcu_bootup_announce(); #ifdef CONFIG_RCU_CPU_STALL_DETECTOR printk(KERN_INFO "RCU-based detection of stalled CPUs is enabled.\n"); @@ -1605,6 +1709,4 @@ void __init __rcu_init(void) open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); } -module_param(blimit, int, 0); -module_param(qhimark, int, 0); -module_param(qlowmark, int, 0); +#include "rcutree_plugin.h" diff --git a/kernel/rcutree.h b/kernel/rcutree.h index 8e8287a983c2..b40ac5706040 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -48,14 +48,14 @@ #elif NR_CPUS <= RCU_FANOUT_SQ # define NUM_RCU_LVLS 2 # define NUM_RCU_LVL_0 1 -# define NUM_RCU_LVL_1 (((NR_CPUS) + RCU_FANOUT - 1) / RCU_FANOUT) +# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT) # define NUM_RCU_LVL_2 (NR_CPUS) # define NUM_RCU_LVL_3 0 #elif NR_CPUS <= RCU_FANOUT_CUBE # define NUM_RCU_LVLS 3 # define NUM_RCU_LVL_0 1 -# define NUM_RCU_LVL_1 (((NR_CPUS) + RCU_FANOUT_SQ - 1) / RCU_FANOUT_SQ) -# define NUM_RCU_LVL_2 (((NR_CPUS) + (RCU_FANOUT) - 1) / (RCU_FANOUT)) +# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_SQ) +# define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT) # define NUM_RCU_LVL_3 NR_CPUS #else # error "CONFIG_RCU_FANOUT insufficient for NR_CPUS" @@ -79,15 +79,21 @@ struct rcu_dynticks { * Definition for node within the RCU grace-period-detection hierarchy. */ struct rcu_node { - spinlock_t lock; + spinlock_t lock; /* Root rcu_node's lock protects some */ + /* rcu_state fields as well as following. */ long gpnum; /* Current grace period for this node. */ /* This will either be equal to or one */ /* behind the root rcu_node's gpnum. */ unsigned long qsmask; /* CPUs or groups that need to switch in */ /* order for current grace period to proceed.*/ + /* In leaf rcu_node, each bit corresponds to */ + /* an rcu_data structure, otherwise, each */ + /* bit corresponds to a child rcu_node */ + /* structure. */ unsigned long qsmaskinit; /* Per-GP initialization for qsmask. */ unsigned long grpmask; /* Mask to apply to parent qsmask. */ + /* Only one bit will be set in this mask. */ int grplo; /* lowest-numbered CPU or group here. */ int grphi; /* highest-numbered CPU or group here. */ u8 grpnum; /* CPU/group number for next level up. */ @@ -95,8 +101,23 @@ struct rcu_node { struct rcu_node *parent; struct list_head blocked_tasks[2]; /* Tasks blocked in RCU read-side critsect. */ + /* Grace period number (->gpnum) x blocked */ + /* by tasks on the (x & 0x1) element of the */ + /* blocked_tasks[] array. */ } ____cacheline_internodealigned_in_smp; +/* + * Do a full breadth-first scan of the rcu_node structures for the + * specified rcu_state structure. + */ +#define rcu_for_each_node_breadth_first(rsp, rnp) \ + for ((rnp) = &(rsp)->node[0]; \ + (rnp) < &(rsp)->node[NUM_RCU_NODES]; (rnp)++) + +#define rcu_for_each_leaf_node(rsp, rnp) \ + for ((rnp) = (rsp)->level[NUM_RCU_LVLS - 1]; \ + (rnp) < &(rsp)->node[NUM_RCU_NODES]; (rnp)++) + /* Index values for nxttail array in struct rcu_data. */ #define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */ #define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */ @@ -126,19 +147,22 @@ struct rcu_data { * Any of the partitions might be empty, in which case the * pointer to that partition will be equal to the pointer for * the following partition. When the list is empty, all of - * the nxttail elements point to nxtlist, which is NULL. + * the nxttail elements point to the ->nxtlist pointer itself, + * which in that case is NULL. * - * [*nxttail[RCU_NEXT_READY_TAIL], NULL = *nxttail[RCU_NEXT_TAIL]): - * Entries that might have arrived after current GP ended - * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]): - * Entries known to have arrived before current GP ended - * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]): - * Entries that batch # <= ->completed - 1: waiting for current GP * [nxtlist, *nxttail[RCU_DONE_TAIL]): * Entries that batch # <= ->completed * The grace period for these entries has completed, and * the other grace-period-completed entries may be moved * here temporarily in rcu_process_callbacks(). + * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]): + * Entries that batch # <= ->completed - 1: waiting for current GP + * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]): + * Entries known to have arrived before current GP ended + * [*nxttail[RCU_NEXT_READY_TAIL], *nxttail[RCU_NEXT_TAIL]): + * Entries that might have arrived after current GP ended + * Note that the value of *nxttail[RCU_NEXT_TAIL] will + * always be NULL, as this is the end of the list. */ struct rcu_head *nxtlist; struct rcu_head **nxttail[RCU_NEXT_SIZE]; @@ -216,8 +240,19 @@ struct rcu_state { /* Force QS state. */ long gpnum; /* Current gp number. */ long completed; /* # of last completed gp. */ + + /* End of fields guarded by root rcu_node's lock. */ + spinlock_t onofflock; /* exclude on/offline and */ - /* starting new GP. */ + /* starting new GP. Also */ + /* protects the following */ + /* orphan_cbs fields. */ + struct rcu_head *orphan_cbs_list; /* list of rcu_head structs */ + /* orphaned by all CPUs in */ + /* a given leaf rcu_node */ + /* going offline. */ + struct rcu_head **orphan_cbs_tail; /* And tail pointer. */ + long orphan_qlen; /* Number of orphaned cbs. */ spinlock_t fqslock; /* Only one task forcing */ /* quiescent states. */ unsigned long jiffies_force_qs; /* Time at which to invoke */ @@ -255,5 +290,30 @@ extern struct rcu_state rcu_preempt_state; DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data); #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */ -#endif /* #ifdef RCU_TREE_NONCORE */ +#else /* #ifdef RCU_TREE_NONCORE */ + +/* Forward declarations for rcutree_plugin.h */ +static inline void rcu_bootup_announce(void); +long rcu_batches_completed(void); +static void rcu_preempt_note_context_switch(int cpu); +static int rcu_preempted_readers(struct rcu_node *rnp); +#ifdef CONFIG_RCU_CPU_STALL_DETECTOR +static void rcu_print_task_stall(struct rcu_node *rnp); +#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ +static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp); +#ifdef CONFIG_HOTPLUG_CPU +static void rcu_preempt_offline_tasks(struct rcu_state *rsp, + struct rcu_node *rnp, + struct rcu_data *rdp); +static void rcu_preempt_offline_cpu(int cpu); +#endif /* #ifdef CONFIG_HOTPLUG_CPU */ +static void rcu_preempt_check_callbacks(int cpu); +static void rcu_preempt_process_callbacks(void); +void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)); +static int rcu_preempt_pending(int cpu); +static int rcu_preempt_needs_cpu(int cpu); +static void __cpuinit rcu_preempt_init_percpu_data(int cpu); +static void rcu_preempt_send_cbs_to_orphanage(void); +static void __init __rcu_init_preempt(void); +#endif /* #else #ifdef RCU_TREE_NONCORE */ diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 1cee04f627eb..c0cb783aa16a 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -150,6 +150,16 @@ void __rcu_read_lock(void) } EXPORT_SYMBOL_GPL(__rcu_read_lock); +/* + * Check for preempted RCU readers blocking the current grace period + * for the specified rcu_node structure. If the caller needs a reliable + * answer, it must hold the rcu_node's ->lock. + */ +static int rcu_preempted_readers(struct rcu_node *rnp) +{ + return !list_empty(&rnp->blocked_tasks[rnp->gpnum & 0x1]); +} + static void rcu_read_unlock_special(struct task_struct *t) { int empty; @@ -196,7 +206,7 @@ static void rcu_read_unlock_special(struct task_struct *t) break; spin_unlock(&rnp->lock); /* irqs remain disabled. */ } - empty = list_empty(&rnp->blocked_tasks[rnp->gpnum & 0x1]); + empty = !rcu_preempted_readers(rnp); list_del_init(&t->rcu_node_entry); t->rcu_blocked_node = NULL; @@ -207,7 +217,7 @@ static void rcu_read_unlock_special(struct task_struct *t) * drop rnp->lock and restore irq. */ if (!empty && rnp->qsmask == 0 && - list_empty(&rnp->blocked_tasks[rnp->gpnum & 0x1])) { + !rcu_preempted_readers(rnp)) { struct rcu_node *rnp_p; if (rnp->parent == NULL) { @@ -257,12 +267,12 @@ static void rcu_print_task_stall(struct rcu_node *rnp) { unsigned long flags; struct list_head *lp; - int phase = rnp->gpnum & 0x1; + int phase; struct task_struct *t; - if (!list_empty(&rnp->blocked_tasks[phase])) { + if (rcu_preempted_readers(rnp)) { spin_lock_irqsave(&rnp->lock, flags); - phase = rnp->gpnum & 0x1; /* re-read under lock. */ + phase = rnp->gpnum & 0x1; lp = &rnp->blocked_tasks[phase]; list_for_each_entry(t, lp, rcu_node_entry) printk(" P%d", t->pid); @@ -281,20 +291,10 @@ static void rcu_print_task_stall(struct rcu_node *rnp) */ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp) { - WARN_ON_ONCE(!list_empty(&rnp->blocked_tasks[rnp->gpnum & 0x1])); + WARN_ON_ONCE(rcu_preempted_readers(rnp)); WARN_ON_ONCE(rnp->qsmask); } -/* - * Check for preempted RCU readers for the specified rcu_node structure. - * If the caller needs a reliable answer, it must hold the rcu_node's - * >lock. - */ -static int rcu_preempted_readers(struct rcu_node *rnp) -{ - return !list_empty(&rnp->blocked_tasks[rnp->gpnum & 0x1]); -} - #ifdef CONFIG_HOTPLUG_CPU /* @@ -410,6 +410,15 @@ static int rcu_preempt_needs_cpu(int cpu) return !!per_cpu(rcu_preempt_data, cpu).nxtlist; } +/** + * rcu_barrier - Wait until all in-flight call_rcu() callbacks complete. + */ +void rcu_barrier(void) +{ + _rcu_barrier(&rcu_preempt_state, call_rcu); +} +EXPORT_SYMBOL_GPL(rcu_barrier); + /* * Initialize preemptable RCU's per-CPU data. */ @@ -419,6 +428,22 @@ static void __cpuinit rcu_preempt_init_percpu_data(int cpu) } /* + * Move preemptable RCU's callbacks to ->orphan_cbs_list. + */ +static void rcu_preempt_send_cbs_to_orphanage(void) +{ + rcu_send_cbs_to_orphanage(&rcu_preempt_state); +} + +/* + * Initialize preemptable RCU's state structures. + */ +static void __init __rcu_init_preempt(void) +{ + RCU_INIT_FLAVOR(&rcu_preempt_state, rcu_preempt_data); +} + +/* * Check for a task exiting while in a preemptable-RCU read-side * critical section, clean up if so. No need to issue warnings, * as debug_check_no_locks_held() already does this if lockdep @@ -461,6 +486,15 @@ static void rcu_preempt_note_context_switch(int cpu) { } +/* + * Because preemptable RCU does not exist, there are never any preempted + * RCU readers. + */ +static int rcu_preempted_readers(struct rcu_node *rnp) +{ + return 0; +} + #ifdef CONFIG_RCU_CPU_STALL_DETECTOR /* @@ -483,15 +517,6 @@ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp) WARN_ON_ONCE(rnp->qsmask); } -/* - * Because preemptable RCU does not exist, there are never any preempted - * RCU readers. - */ -static int rcu_preempted_readers(struct rcu_node *rnp) -{ - return 0; -} - #ifdef CONFIG_HOTPLUG_CPU /* @@ -518,7 +543,7 @@ static void rcu_preempt_offline_cpu(int cpu) * Because preemptable RCU does not exist, it never has any callbacks * to check. */ -void rcu_preempt_check_callbacks(int cpu) +static void rcu_preempt_check_callbacks(int cpu) { } @@ -526,7 +551,7 @@ void rcu_preempt_check_callbacks(int cpu) * Because preemptable RCU does not exist, it never has any callbacks * to process. */ -void rcu_preempt_process_callbacks(void) +static void rcu_preempt_process_callbacks(void) { } @@ -556,6 +581,16 @@ static int rcu_preempt_needs_cpu(int cpu) } /* + * Because preemptable RCU does not exist, rcu_barrier() is just + * another name for rcu_barrier_sched(). + */ +void rcu_barrier(void) +{ + rcu_barrier_sched(); +} +EXPORT_SYMBOL_GPL(rcu_barrier); + +/* * Because preemptable RCU does not exist, there is no per-CPU * data to initialize. */ @@ -563,4 +598,18 @@ static void __cpuinit rcu_preempt_init_percpu_data(int cpu) { } +/* + * Because there is no preemptable RCU, there are no callbacks to move. + */ +static void rcu_preempt_send_cbs_to_orphanage(void) +{ +} + +/* + * Because preemptable RCU does not exist, it need not be initialized. + */ +static void __init __rcu_init_preempt(void) +{ +} + #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */ diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c index 179e6ad80dc0..4b31c779e62e 100644 --- a/kernel/rcutree_trace.c +++ b/kernel/rcutree_trace.c @@ -159,13 +159,13 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp) struct rcu_node *rnp; seq_printf(m, "c=%ld g=%ld s=%d jfq=%ld j=%x " - "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu\n", + "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld\n", rsp->completed, rsp->gpnum, rsp->signaled, (long)(rsp->jiffies_force_qs - jiffies), (int)(jiffies & 0xffff), rsp->n_force_qs, rsp->n_force_qs_ngp, rsp->n_force_qs - rsp->n_force_qs_ngp, - rsp->n_force_qs_lh); + rsp->n_force_qs_lh, rsp->orphan_qlen); for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < NUM_RCU_NODES; rnp++) { if (rnp->level != level) { seq_puts(m, "\n"); |