8ae0ae6737
Interrupts and exceptions invoke rcu_irq_enter() on entry and need to invoke rcu_irq_exit() before they either return to the interrupted code or invoke the scheduler due to preemption. The general assumption is that RCU idle code has to have preemption disabled so that a return from interrupt cannot schedule. So the return from interrupt code invokes rcu_irq_exit() and preempt_schedule_irq(). If there is any imbalance in the rcu_irq/nmi* invocations or RCU idle code had preemption enabled then this goes unnoticed until the CPU goes idle or some other RCU check is executed. Provide rcu_irq_exit_preempt() which can be invoked from the interrupt/exception return code in case that preemption is enabled. It invokes rcu_irq_exit() and contains a few sanity checks in case that CONFIG_PROVE_RCU is enabled to catch such issues directly. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200505134904.364456424@linutronix.de
74 lines
2.1 KiB
C
74 lines
2.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* Read-Copy Update mechanism for mutual exclusion (tree-based version)
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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.ibm.com> Hierarchical algorithm
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*
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* Based on the original work by Paul McKenney <paulmck@linux.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_softirq_qs(void);
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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_expedited(void);
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void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func);
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void rcu_barrier(void);
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bool rcu_eqs_special_set(int cpu);
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void rcu_momentary_dyntick_idle(void);
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void kfree_rcu_scheduler_running(void);
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bool rcu_gp_might_be_stalled(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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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_exit_preempt(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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void rcu_end_inkernel_boot(void);
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bool rcu_inkernel_boot_has_ended(void);
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bool rcu_is_watching(void);
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#ifndef CONFIG_PREEMPTION
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void rcu_all_qs(void);
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#endif
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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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void rcu_cpu_starting(unsigned int cpu);
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#endif /* __LINUX_RCUTREE_H */
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