Commit 135c8aea authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Ingo Molnar
Browse files

rcu: Replace the rcu_barrier enum with pointer to call_rcu*() function 



The rcu_barrier enum causes several problems:

  (1) you have to define the enum somewhere, and there is no
      convenient place,

  (2) the difference between TREE_RCU and TREE_PREEMPT_RCU causes
      problems when you need to map from rcu_barrier enum to struct
      rcu_state,

  (3) the switch statement are large, and

  (4) TINY_RCU really needs a different rcu_barrier() than do the
      treercu implementations.

So replace it with a functionally equivalent but cleaner function
pointer abstraction.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: default avatarMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <12541998232366-git-send-email->
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent a0b6c9a7

kernel/rcupdate.c

+10 −22
Original line number Diff line number Diff line
@@ -53,12 +53,6 @@ struct lockdep_map rcu_lock_map = 
EXPORT_SYMBOL_GPL(rcu_lock_map);

#endif



enum rcu_barrier {

	RCU_BARRIER_STD,

	RCU_BARRIER_BH,

	RCU_BARRIER_SCHED,

};



static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL};

static atomic_t rcu_barrier_cpu_count;

static DEFINE_MUTEX(rcu_barrier_mutex);
@@ -184,19 +178,12 @@ static void rcu_barrier_func(void *type) 
{

	int cpu = smp_processor_id();

	struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu);

	void (*call_rcu_func)(struct rcu_head *head,

			      void (*func)(struct rcu_head *head));



	atomic_inc(&rcu_barrier_cpu_count);

	switch ((enum rcu_barrier)type) {

	case RCU_BARRIER_STD:

		call_rcu(head, rcu_barrier_callback);

		break;

	case RCU_BARRIER_BH:

		call_rcu_bh(head, rcu_barrier_callback);

		break;

	case RCU_BARRIER_SCHED:

		call_rcu_sched(head, rcu_barrier_callback);

		break;

	}

	call_rcu_func = type;

	call_rcu_func(head, rcu_barrier_callback);

}



static inline void wait_migrated_callbacks(void)
@@ -209,7 +196,8 @@ static inline void wait_migrated_callbacks(void) 
 * Orchestrate the specified type of RCU barrier, waiting for all

 * RCU callbacks of the specified type to complete.

 */

static void _rcu_barrier(enum rcu_barrier type)

static void _rcu_barrier(void (*call_rcu_func)(struct rcu_head *head,

					       void (*func)(struct rcu_head *head)))

{

	BUG_ON(in_interrupt());

	/* Take cpucontrol mutex to protect against CPU hotplug */
@@ -225,7 +213,7 @@ static void _rcu_barrier(enum rcu_barrier type) 
	 * early.

	 */

	atomic_set(&rcu_barrier_cpu_count, 1);

	on_each_cpu(rcu_barrier_func, (void *)type, 1);

	on_each_cpu(rcu_barrier_func, (void *)call_rcu_func, 1);

	if (atomic_dec_and_test(&rcu_barrier_cpu_count))

		complete(&rcu_barrier_completion);

	wait_for_completion(&rcu_barrier_completion);
@@ -238,7 +226,7 @@ static void _rcu_barrier(enum rcu_barrier type) 
 */

void rcu_barrier(void)

{

	_rcu_barrier(RCU_BARRIER_STD);

	_rcu_barrier(call_rcu);

}

EXPORT_SYMBOL_GPL(rcu_barrier);
@@ -247,7 +235,7 @@ EXPORT_SYMBOL_GPL(rcu_barrier); 
 */

void rcu_barrier_bh(void)

{

	_rcu_barrier(RCU_BARRIER_BH);

	_rcu_barrier(call_rcu_bh);

}

EXPORT_SYMBOL_GPL(rcu_barrier_bh);
@@ -256,7 +244,7 @@ EXPORT_SYMBOL_GPL(rcu_barrier_bh); 
 */

void rcu_barrier_sched(void)

{

	_rcu_barrier(RCU_BARRIER_SCHED);

	_rcu_barrier(call_rcu_sched);

}

EXPORT_SYMBOL_GPL(rcu_barrier_sched);

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