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: Paul 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: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/ia64/xen/time.c b/arch/ia64/xen/time.c
index fb83326..dbeadb9 100644
--- a/arch/ia64/xen/time.c
+++ b/arch/ia64/xen/time.c
@@ -133,8 +133,7 @@
account_idle_ticks(blocked);
run_local_timers();
- if (rcu_pending(cpu))
- rcu_check_callbacks(cpu, user_mode(get_irq_regs()));
+ rcu_check_callbacks(cpu, user_mode(get_irq_regs()));
scheduler_tick();
run_posix_cpu_timers(p);
diff --git a/include/linux/rcupreempt.h b/include/linux/rcupreempt.h
index 6c9dd9c..aff4772 100644
--- a/include/linux/rcupreempt.h
+++ b/include/linux/rcupreempt.h
@@ -66,7 +66,6 @@
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(); }
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 8a0222c..c739d90 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -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)
diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c
index 7d777c9..0053ce5 100644
--- a/kernel/rcupreempt.c
+++ b/kernel/rcupreempt.c
@@ -159,6 +159,8 @@
.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 @@
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 @@
* 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 @@
rdp->waitschedlist != NULL);
}
-int rcu_pending(int cpu)
+static int rcu_pending(int cpu)
{
struct rcu_data *rdp = RCU_DATA_CPU(cpu);
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 7c51508..4ce3adc 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -111,6 +111,7 @@
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 @@
*/
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 @@
* 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));
diff --git a/kernel/timer.c b/kernel/timer.c
index a7f07d5..a3d25f415 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1156,8 +1156,7 @@
/* Note: this timer irq context must be accounted for as well. */
account_process_tick(p, user_tick);
run_local_timers();
- if (rcu_pending(cpu))
- rcu_check_callbacks(cpu, user_tick);
+ rcu_check_callbacks(cpu, user_tick);
printk_tick();
scheduler_tick();
run_posix_cpu_timers(p);
