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Commit 07899a6e authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Paul E. McKenney
Browse files

rcu_sync: Introduce rcu_sync_dtor() 



This commit allows rcu_sync structures to be safely deallocated,
The trick is to add a new ->wait field to the gp_ops array.
This field is a pointer to the rcu_barrier() function corresponding
to the flavor of RCU in question.  This allows a new rcu_sync_dtor()
to wait for any outstanding callbacks before freeing the rcu_sync
structure.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent 3a518b76

include/linux/rcu_sync.h

+1 −0
Original line number Diff line number Diff line
@@ -62,6 +62,7 @@ static inline bool rcu_sync_is_idle(struct rcu_sync *rsp) 
extern void rcu_sync_init(struct rcu_sync *, enum rcu_sync_type);

extern void rcu_sync_enter(struct rcu_sync *);

extern void rcu_sync_exit(struct rcu_sync *);

extern void rcu_sync_dtor(struct rcu_sync *);



#define __RCU_SYNC_INITIALIZER(name, type) {				\

		.gp_state = 0,						\

kernel/rcu/sync.c

+26 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ 
static const struct {

	void (*sync)(void);

	void (*call)(struct rcu_head *, void (*)(struct rcu_head *));

	void (*wait)(void);

#ifdef CONFIG_PROVE_RCU

	int  (*held)(void);

#endif
@@ -39,16 +40,19 @@ static const struct { 
	[RCU_SYNC] = {

		.sync = synchronize_rcu,

		.call = call_rcu,

		.wait = rcu_barrier,

		__INIT_HELD(rcu_read_lock_held)

	},

	[RCU_SCHED_SYNC] = {

		.sync = synchronize_sched,

		.call = call_rcu_sched,

		.wait = rcu_barrier_sched,

		__INIT_HELD(rcu_read_lock_sched_held)

	},

	[RCU_BH_SYNC] = {

		.sync = synchronize_rcu_bh,

		.call = call_rcu_bh,

		.wait = rcu_barrier_bh,

		__INIT_HELD(rcu_read_lock_bh_held)

	},

};
@@ -195,3 +199,25 @@ void rcu_sync_exit(struct rcu_sync *rsp) 
	}

	spin_unlock_irq(&rsp->rss_lock);

}



/**

 * rcu_sync_dtor() - Clean up an rcu_sync structure

 * @rsp: Pointer to rcu_sync structure to be cleaned up

 */

void rcu_sync_dtor(struct rcu_sync *rsp)

{

	int cb_state;



	BUG_ON(rsp->gp_count);



	spin_lock_irq(&rsp->rss_lock);

	if (rsp->cb_state == CB_REPLAY)

		rsp->cb_state = CB_PENDING;

	cb_state = rsp->cb_state;

	spin_unlock_irq(&rsp->rss_lock);



	if (cb_state != CB_IDLE) {

		gp_ops[rsp->gp_type].wait();

		BUG_ON(rsp->cb_state != CB_IDLE);

	}

}