rcu: Add RCU-sched flavors of get-state and cond-sync (24560056) · Commits · 戴 / test

include/linux/rcutiny.h

+10 −0

Original line number	Diff line number	Diff line
		@@ -37,6 +37,16 @@ static inline void cond_synchronize_rcu(unsigned long oldstate)
		might_sleep();
		}

		static inline unsigned long get_state_synchronize_sched(void)
		{
		return 0;
		}

		static inline void cond_synchronize_sched(unsigned long oldstate)
		{
		might_sleep();
		}

		static inline void rcu_barrier_bh(void)
		{
		wait_rcu_gp(call_rcu_bh);

include/linux/rcutree.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -76,6 +76,8 @@ void rcu_barrier_bh(void);
		void rcu_barrier_sched(void);
		unsigned long get_state_synchronize_rcu(void);
		void cond_synchronize_rcu(unsigned long oldstate);
		unsigned long get_state_synchronize_sched(void);
		void cond_synchronize_sched(unsigned long oldstate);

		extern unsigned long rcutorture_testseq;
		extern unsigned long rcutorture_vernum;

kernel/rcu/rcutorture.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -635,6 +635,8 @@ static struct rcu_torture_ops sched_ops = {
		.deferred_free = rcu_sched_torture_deferred_free,
		.sync = synchronize_sched,
		.exp_sync = synchronize_sched_expedited,
		.get_state = get_state_synchronize_sched,
		.cond_sync = cond_synchronize_sched,
		.call = call_rcu_sched,
		.cb_barrier = rcu_barrier_sched,
		.fqs = rcu_sched_force_quiescent_state,

kernel/rcu/tree.c

+52 −0

Original line number	Diff line number	Diff line
		@@ -3253,6 +3253,58 @@ void cond_synchronize_rcu(unsigned long oldstate)
		}
		EXPORT_SYMBOL_GPL(cond_synchronize_rcu);

		/**
		* get_state_synchronize_sched - Snapshot current RCU-sched state
		*
		* Returns a cookie that is used by a later call to cond_synchronize_sched()
		* to determine whether or not a full grace period has elapsed in the
		* meantime.
		*/
		unsigned long get_state_synchronize_sched(void)
		{
		/*
		* Any prior manipulation of RCU-protected data must happen
		* before the load from ->gpnum.
		*/
		smp_mb(); /* ^^^ */

		/*
		* Make sure this load happens before the purportedly
		* time-consuming work between get_state_synchronize_sched()
		* and cond_synchronize_sched().
		*/
		return smp_load_acquire(&rcu_sched_state.gpnum);
		}
		EXPORT_SYMBOL_GPL(get_state_synchronize_sched);

		/**
		* cond_synchronize_sched - Conditionally wait for an RCU-sched grace period
		*
		* @oldstate: return value from earlier call to get_state_synchronize_sched()
		*
		* If a full RCU-sched grace period has elapsed since the earlier call to
		* get_state_synchronize_sched(), just return. Otherwise, invoke
		* synchronize_sched() to wait for a full grace period.
		*
		* Yes, this function does not take counter wrap into account. But
		* counter wrap is harmless. If the counter wraps, we have waited for
		* more than 2 billion grace periods (and way more on a 64-bit system!),
		* so waiting for one additional grace period should be just fine.
		*/
		void cond_synchronize_sched(unsigned long oldstate)
		{
		unsigned long newstate;

		/*
		* Ensure that this load happens before any RCU-destructive
		* actions the caller might carry out after we return.
		*/
		newstate = smp_load_acquire(&rcu_sched_state.completed);
		if (ULONG_CMP_GE(oldstate, newstate))
		synchronize_sched();
		}
		EXPORT_SYMBOL_GPL(cond_synchronize_sched);

		static int synchronize_sched_expedited_cpu_stop(void *data)
		{
		/*

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