diff options
| -rw-r--r-- | kernel/rcu/tree.c | 74 |
1 files changed, 32 insertions, 42 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 5e14a19c066c..c8761e7c7c00 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -382,12 +382,11 @@ static int rcu_is_cpu_rrupt_from_idle(void) } /* - * Register a quiescent state for all RCU flavors. If there is an + * Register an urgently needed quiescent state. If there is an * emergency, invoke rcu_momentary_dyntick_idle() to do a heavy-weight - * dyntick-idle quiescent state visible to other CPUs (but only for those - * RCU flavors in desperate need of a quiescent state, which will normally - * be none of them). Either way, do a lightweight quiescent state for - * all RCU flavors. + * dyntick-idle quiescent state visible to other CPUs, which will in + * some cases serve for expedited as well as normal grace periods. + * Either way, register a lightweight quiescent state. * * The barrier() calls are redundant in the common case when this is * called externally, but just in case this is called from within this @@ -564,7 +563,7 @@ void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags, EXPORT_SYMBOL_GPL(rcutorture_get_gp_data); /* - * Return the root node of the specified rcu_state structure. + * Return the root node of the rcu_state structure. */ static struct rcu_node *rcu_get_root(void) { @@ -949,11 +948,7 @@ void rcu_request_urgent_qs_task(struct task_struct *t) * Disable preemption to avoid false positives that could otherwise * happen due to the current CPU number being sampled, this task being * preempted, its old CPU being taken offline, resuming on some other CPU, - * then determining that its old CPU is now offline. Because there are - * multiple flavors of RCU, and because this function can be called in the - * midst of updating the flavors while a given CPU coming online or going - * offline, it is necessary to check all flavors. If any of the flavors - * believe that given CPU is online, it is considered to be online. + * then determining that its old CPU is now offline. * * Disable checking if in an NMI handler because we cannot safely * report errors from NMI handlers anyway. In addition, it is OK to use @@ -1563,11 +1558,10 @@ static bool rcu_future_gp_cleanup(struct rcu_node *rnp) } /* - * Awaken the grace-period kthread for the specified flavor of RCU. - * Don't do a self-awaken, and don't bother awakening when there is - * nothing for the grace-period kthread to do (as in several CPUs - * raced to awaken, and we lost), and finally don't try to awaken - * a kthread that has not yet been created. + * Awaken the grace-period kthread. Don't do a self-awaken, and don't + * bother awakening when there is nothing for the grace-period kthread + * to do (as in several CPUs raced to awaken, and we lost), and finally + * don't try to awaken a kthread that has not yet been created. */ static void rcu_gp_kthread_wake(void) { @@ -2119,13 +2113,13 @@ static int __noreturn rcu_gp_kthread(void *unused) } /* - * Report a full set of quiescent states to the specified rcu_state data - * structure. Invoke rcu_gp_kthread_wake() to awaken the grace-period - * kthread if another grace period is required. Whether we wake - * the grace-period kthread or it awakens itself for the next round - * of quiescent-state forcing, that kthread will clean up after the - * just-completed grace period. Note that the caller must hold rnp->lock, - * which is released before return. + * Report a full set of quiescent states to the rcu_state data structure. + * Invoke rcu_gp_kthread_wake() to awaken the grace-period kthread if + * another grace period is required. Whether we wake the grace-period + * kthread or it awakens itself for the next round of quiescent-state + * forcing, that kthread will clean up after the just-completed grace + * period. Note that the caller must hold rnp->lock, which is released + * before return. */ static void rcu_report_qs_rsp(unsigned long flags) __releases(rcu_get_root()->lock) @@ -2212,7 +2206,7 @@ static void rcu_report_qs_rnp(unsigned long mask, struct rcu_node *rnp, /* * Record a quiescent state for all tasks that were previously queued * on the specified rcu_node structure and that were blocking the current - * RCU grace period. The caller must hold the specified rnp->lock with + * RCU grace period. The caller must hold the corresponding rnp->lock with * irqs disabled, and this lock is released upon return, but irqs remain * disabled. */ @@ -2714,11 +2708,11 @@ static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused } /* - * Schedule RCU callback invocation. If the specified type of RCU - * does not support RCU priority boosting, just do a direct call, - * otherwise wake up the per-CPU kernel kthread. Note that because we - * are running on the current CPU with softirqs disabled, the - * rcu_cpu_kthread_task cannot disappear out from under us. + * Schedule RCU callback invocation. If the running implementation of RCU + * does not support RCU priority boosting, just do a direct call, otherwise + * wake up the per-CPU kernel kthread. Note that because we are running + * on the current CPU with softirqs disabled, the rcu_cpu_kthread_task + * cannot disappear out from under us. */ static void invoke_rcu_callbacks(struct rcu_data *rdp) { @@ -2959,11 +2953,10 @@ EXPORT_SYMBOL_GPL(cond_synchronize_rcu); /* * Check to see if there is any immediate RCU-related work to be done by - * the current CPU, for the specified type of RCU, returning 1 if so and - * zero otherwise. The checks are in order of increasing expense: checks - * that can be carried out against CPU-local state are performed first. - * However, we must check for CPU stalls first, else we might not get - * a chance. + * the current CPU, returning 1 if so and zero otherwise. The checks are + * in order of increasing expense: checks that can be carried out against + * CPU-local state are performed first. However, we must check for CPU + * stalls first, else we might not get a chance. */ static int rcu_pending(void) { @@ -3070,10 +3063,7 @@ static void rcu_barrier_func(void *unused) } } -/* - * Orchestrate the specified type of RCU barrier, waiting for all - * RCU callbacks of the specified type to complete. - */ +/* Orchestrate an RCU barrier, waiting for all RCU callbacks to complete. */ static void _rcu_barrier(void) { int cpu; @@ -3393,7 +3383,7 @@ void rcu_report_dead(unsigned int cpu) struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rdp & rnp. */ - /* QS for any half-done expedited RCU-sched GP. */ + /* QS for any half-done expedited grace period. */ preempt_disable(); rcu_report_exp_rdp(this_cpu_ptr(&rcu_data)); preempt_enable(); @@ -3482,7 +3472,7 @@ static int rcu_pm_notify(struct notifier_block *self, } /* - * Spawn the kthreads that handle each RCU flavor's grace periods. + * Spawn the kthreads that handle RCU's grace periods. */ static int __init rcu_spawn_gp_kthread(void) { @@ -3545,7 +3535,7 @@ void rcu_scheduler_starting(void) } /* - * Helper function for rcu_init() that initializes one rcu_state structure. + * Helper function for rcu_init() that initializes the rcu_state structure. */ static void __init rcu_init_one(void) { @@ -3707,7 +3697,7 @@ static void __init rcu_init_geometry(void) /* * Dump out the structure of the rcu_node combining tree associated - * with the rcu_state structure referenced by rsp. + * with the rcu_state structure. */ static void __init rcu_dump_rcu_node_tree(void) { |
