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bcbfdd01dc
Currently, a call to schedule() acts as a Tasks RCU quiescent state only if a context switch actually takes place. However, just the call to schedule() guarantees that the calling task has moved off of whatever tracing trampoline that it might have been one previously. This commit therefore plumbs schedule()'s "preempt" parameter into rcu_note_context_switch(), which then records the Tasks RCU quiescent state, but only if this call to schedule() was -not- due to a preemption. To avoid adding overhead to the common-case context-switch path, this commit hides the rcu_note_context_switch() check under an existing non-common-case check. Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
123 lines
4.1 KiB
C
123 lines
4.1 KiB
C
/*
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* Read-Copy Update mechanism for mutual exclusion (tree-based version)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, you can access it online at
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* http://www.gnu.org/licenses/gpl-2.0.html.
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*
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* Copyright IBM Corporation, 2008
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*
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* Author: Dipankar Sarma <dipankar@in.ibm.com>
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* Paul E. McKenney <paulmck@linux.vnet.ibm.com> Hierarchical algorithm
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*
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* Based on the original work by Paul McKenney <paulmck@us.ibm.com>
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* and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
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*
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* For detailed explanation of Read-Copy Update mechanism see -
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* Documentation/RCU
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*/
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#ifndef __LINUX_RCUTREE_H
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#define __LINUX_RCUTREE_H
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void rcu_note_context_switch(bool preempt);
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int rcu_needs_cpu(u64 basem, u64 *nextevt);
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void rcu_cpu_stall_reset(void);
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/*
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* Note a virtualization-based context switch. This is simply a
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* wrapper around rcu_note_context_switch(), which allows TINY_RCU
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* to save a few bytes. The caller must have disabled interrupts.
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*/
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static inline void rcu_virt_note_context_switch(int cpu)
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{
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rcu_note_context_switch(false);
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}
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void synchronize_rcu_bh(void);
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void synchronize_sched_expedited(void);
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void synchronize_rcu_expedited(void);
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void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func);
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/**
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* synchronize_rcu_bh_expedited - Brute-force RCU-bh grace period
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*
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* Wait for an RCU-bh grace period to elapse, but use a "big hammer"
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* approach to force the grace period to end quickly. This consumes
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* significant time on all CPUs and is unfriendly to real-time workloads,
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* so is thus not recommended for any sort of common-case code. In fact,
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* if you are using synchronize_rcu_bh_expedited() in a loop, please
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* restructure your code to batch your updates, and then use a single
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* synchronize_rcu_bh() instead.
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*
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* Note that it is illegal to call this function while holding any lock
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* that is acquired by a CPU-hotplug notifier. And yes, it is also illegal
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* to call this function from a CPU-hotplug notifier. Failing to observe
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* these restriction will result in deadlock.
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*/
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static inline void synchronize_rcu_bh_expedited(void)
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{
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synchronize_sched_expedited();
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}
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void rcu_barrier(void);
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void rcu_barrier_bh(void);
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void rcu_barrier_sched(void);
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unsigned long get_state_synchronize_rcu(void);
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void cond_synchronize_rcu(unsigned long oldstate);
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unsigned long get_state_synchronize_sched(void);
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void cond_synchronize_sched(unsigned long oldstate);
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extern unsigned long rcutorture_testseq;
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extern unsigned long rcutorture_vernum;
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unsigned long rcu_batches_started(void);
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unsigned long rcu_batches_started_bh(void);
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unsigned long rcu_batches_started_sched(void);
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unsigned long rcu_batches_completed(void);
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unsigned long rcu_batches_completed_bh(void);
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unsigned long rcu_batches_completed_sched(void);
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unsigned long rcu_exp_batches_completed(void);
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unsigned long rcu_exp_batches_completed_sched(void);
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void show_rcu_gp_kthreads(void);
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void rcu_force_quiescent_state(void);
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void rcu_bh_force_quiescent_state(void);
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void rcu_sched_force_quiescent_state(void);
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void rcu_idle_enter(void);
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void rcu_idle_exit(void);
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void rcu_irq_enter(void);
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void rcu_irq_exit(void);
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void rcu_irq_enter_irqson(void);
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void rcu_irq_exit_irqson(void);
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void exit_rcu(void);
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void rcu_scheduler_starting(void);
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extern int rcu_scheduler_active __read_mostly;
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bool rcu_is_watching(void);
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void rcu_request_urgent_qs_task(struct task_struct *t);
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void rcu_all_qs(void);
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/* RCUtree hotplug events */
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int rcutree_prepare_cpu(unsigned int cpu);
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int rcutree_online_cpu(unsigned int cpu);
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int rcutree_offline_cpu(unsigned int cpu);
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int rcutree_dead_cpu(unsigned int cpu);
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int rcutree_dying_cpu(unsigned int cpu);
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#endif /* __LINUX_RCUTREE_H */
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