rcu: Define rcu_all_qs() only in !PREEMPT builds (395a2f09) · Commits · 戴 / test

include/linux/rcutree.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -66,7 +66,9 @@ void rcu_scheduler_starting(void);
		extern int rcu_scheduler_active __read_mostly;
		void rcu_end_inkernel_boot(void);
		bool rcu_is_watching(void);
		#ifndef CONFIG_PREEMPT
		void rcu_all_qs(void);
		#endif

		/* RCUtree hotplug events */
		int rcutree_prepare_cpu(unsigned int cpu);

kernel/rcu/tree.c

+1 −40

Original line number	Diff line number	Diff line
		@@ -356,7 +356,7 @@ bool rcu_eqs_special_set(int cpu)
		*
		* The caller must have disabled interrupts and must not be idle.
		*/
		static void rcu_momentary_dyntick_idle(void)
		static void __maybe_unused rcu_momentary_dyntick_idle(void)
		{
		struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
		int special;
		@@ -381,45 +381,6 @@ static int rcu_is_cpu_rrupt_from_idle(void)
		__this_cpu_read(rcu_dynticks.dynticks_nmi_nesting) <= 1;
		}

		/*
		* 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, 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
		* file.
		*
		*/
		void rcu_all_qs(void)
		{
		unsigned long flags;

		if (!raw_cpu_read(rcu_dynticks.rcu_urgent_qs))
		return;
		preempt_disable();
		/* Load rcu_urgent_qs before other flags. */
		if (!smp_load_acquire(this_cpu_ptr(&rcu_dynticks.rcu_urgent_qs))) {
		preempt_enable();
		return;
		}
		this_cpu_write(rcu_dynticks.rcu_urgent_qs, false);
		barrier(); /* Avoid RCU read-side critical sections leaking down. */
		if (unlikely(raw_cpu_read(rcu_dynticks.rcu_need_heavy_qs))) {
		local_irq_save(flags);
		rcu_momentary_dyntick_idle();
		local_irq_restore(flags);
		}
		if (unlikely(raw_cpu_read(rcu_data.cpu_no_qs.b.exp)))
		rcu_qs();
		this_cpu_inc(rcu_dynticks.rcu_qs_ctr);
		barrier(); /* Avoid RCU read-side critical sections leaking up. */
		preempt_enable();
		}
		EXPORT_SYMBOL_GPL(rcu_all_qs);

		#define DEFAULT_RCU_BLIMIT 10 /* Maximum callbacks per rcu_do_batch. */
		static long blimit = DEFAULT_RCU_BLIMIT;
		#define DEFAULT_RCU_QHIMARK 10000 /* If this many pending, ignore blimit. */

kernel/rcu/tree_plugin.h

+39 −0

Original line number	Diff line number	Diff line
		@@ -947,6 +947,45 @@ static void rcu_qs(void)
		rcu_report_exp_rdp(this_cpu_ptr(&rcu_data));
		}

		/*
		* 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, 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
		* file.
		*
		*/
		void rcu_all_qs(void)
		{
		unsigned long flags;

		if (!raw_cpu_read(rcu_dynticks.rcu_urgent_qs))
		return;
		preempt_disable();
		/* Load rcu_urgent_qs before other flags. */
		if (!smp_load_acquire(this_cpu_ptr(&rcu_dynticks.rcu_urgent_qs))) {
		preempt_enable();
		return;
		}
		this_cpu_write(rcu_dynticks.rcu_urgent_qs, false);
		barrier(); /* Avoid RCU read-side critical sections leaking down. */
		if (unlikely(raw_cpu_read(rcu_dynticks.rcu_need_heavy_qs))) {
		local_irq_save(flags);
		rcu_momentary_dyntick_idle();
		local_irq_restore(flags);
		}
		if (unlikely(raw_cpu_read(rcu_data.cpu_no_qs.b.exp)))
		rcu_qs();
		this_cpu_inc(rcu_dynticks.rcu_qs_ctr);
		barrier(); /* Avoid RCU read-side critical sections leaking up. */
		preempt_enable();
		}
		EXPORT_SYMBOL_GPL(rcu_all_qs);

		/*
		* Note a PREEMPT=n context switch. The caller must have disabled interrupts.
		*/

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