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Commit a157229c authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Ingo Molnar
Browse files

rcu: Simplify rcu_pending()/rcu_check_callbacks() API 



All calls from outside RCU are of the form:

	if (rcu_pending(cpu))
		rcu_check_callbacks(cpu, user);

This is silly, instead we put a call to rcu_pending() in
rcu_check_callbacks(), and then make the outside calls be to
rcu_check_callbacks().  This cuts down on the code a bit and
also gives the compiler a better chance of optimizing.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: mathieu.desnoyers@polymtl.ca
Cc: josht@linux.vnet.ibm.com
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
LKML-Reference: <125097461311-git-send-email->
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 22f00b69

arch/ia64/xen/time.c

+1 −2
Original line number Diff line number Diff line
@@ -133,7 +133,6 @@ consider_steal_time(unsigned long new_itm) 
		account_idle_ticks(blocked);

		run_local_timers();



		if (rcu_pending(cpu))

		rcu_check_callbacks(cpu, user_mode(get_irq_regs()));



		scheduler_tick();

include/linux/rcupreempt.h

+0 −1
Original line number Diff line number Diff line
@@ -66,7 +66,6 @@ extern void call_rcu_sched(struct rcu_head *head, 


extern void __rcu_read_lock(void);

extern void __rcu_read_unlock(void);

extern int rcu_pending(int cpu);

extern int rcu_needs_cpu(int cpu);



#define __rcu_read_lock_bh()	{ rcu_read_lock(); local_bh_disable(); }

include/linux/rcutree.h

+0 −1
Original line number Diff line number Diff line
@@ -33,7 +33,6 @@ 
extern void rcu_sched_qs(int cpu);

extern void rcu_bh_qs(int cpu);



extern int rcu_pending(int cpu);

extern int rcu_needs_cpu(int cpu);



static inline void __rcu_read_lock(void)

kernel/rcupreempt.c

+8 −2
Original line number Diff line number Diff line
@@ -159,6 +159,8 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_dyntick_sched, rcu_dyntick_sched 
	.dynticks = 1,

};



static int rcu_pending(int cpu);



void rcu_sched_qs(int cpu)

{

	struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu);
@@ -961,7 +963,10 @@ static void rcu_check_mb(int cpu) 
void rcu_check_callbacks(int cpu, int user)

{

	unsigned long flags;

	struct rcu_data *rdp = RCU_DATA_CPU(cpu);

	struct rcu_data *rdp;



	if (!rcu_pending(cpu))

		return; /* if nothing for RCU to do. */



	/*

	 * If this CPU took its interrupt from user mode or from the
@@ -976,6 +981,7 @@ void rcu_check_callbacks(int cpu, int user) 
	 * CPUs to happen after any such write.

	 */



	rdp = RCU_DATA_CPU(cpu);

	if (user ||

	    (idle_cpu(cpu) && !in_softirq() &&

	     hardirq_count() <= (1 << HARDIRQ_SHIFT))) {
@@ -1382,7 +1388,7 @@ int rcu_needs_cpu(int cpu) 
		rdp->waitschedlist != NULL);

}



int rcu_pending(int cpu)

static int rcu_pending(int cpu)

{

	struct rcu_data *rdp = RCU_DATA_CPU(cpu);

kernel/rcutree.c

+4 −1
Original line number Diff line number Diff line
@@ -111,6 +111,7 @@ static int qhimark = 10000; /* If this many pending, ignore blimit. */ 
static int qlowmark = 100;	/* Once only this many pending, use blimit. */



static void force_quiescent_state(struct rcu_state *rsp, int relaxed);

static int rcu_pending(int cpu);



/*

 * Return the number of RCU-sched batches processed thus far for debug & stats.
@@ -974,6 +975,8 @@ static void rcu_do_batch(struct rcu_data *rdp) 
 */

void rcu_check_callbacks(int cpu, int user)

{

	if (!rcu_pending(cpu))

		return; /* if nothing for RCU to do. */

	if (user ||

	    (idle_cpu(cpu) && rcu_scheduler_active &&

	     !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) {
@@ -1329,7 +1332,7 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) 
 * by the current CPU, returning 1 if so.  This function is part of the

 * RCU implementation; it is -not- an exported member of the RCU API.

 */

int rcu_pending(int cpu)

static int rcu_pending(int cpu)

{

	return __rcu_pending(&rcu_sched_state, &per_cpu(rcu_sched_data, cpu)) ||

	       __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu));