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Subject[PATCH tip/core/rcu 04/15] rcu: Place pointer to call_rcu() in rcu_data structure
Date
From: "Paul E. McKenney" <paul.mckenney@linaro.org>

This is a preparatory commit for increasing rcu_barrier()'s concurrency.
It adds a pointer in the rcu_data structure to the corresponding call_rcu()
function. This allows a pointer to the rcu_data structure to imply the
function pointer, which allows _rcu_barrier() state to be placed in the
rcu_state structure.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcutree.c | 27 ++++++++++++---------------
kernel/rcutree.h | 2 ++
kernel/rcutree_plugin.h | 5 +++--
3 files changed, 17 insertions(+), 17 deletions(-)
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 8ce1b1d..8b3ab4e 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -62,8 +62,9 @@

static struct lock_class_key rcu_node_class[RCU_NUM_LVLS];

-#define RCU_STATE_INITIALIZER(sname) { \
+#define RCU_STATE_INITIALIZER(sname, cr) { \
.level = { &sname##_state.node[0] }, \
+ .call = cr, \
.fqs_state = RCU_GP_IDLE, \
.gpnum = -300, \
.completed = -300, \
@@ -76,10 +77,11 @@ static struct lock_class_key rcu_node_class[RCU_NUM_LVLS];
.name = #sname, \
}

-struct rcu_state rcu_sched_state = RCU_STATE_INITIALIZER(rcu_sched);
+struct rcu_state rcu_sched_state =
+ RCU_STATE_INITIALIZER(rcu_sched, call_rcu_sched);
DEFINE_PER_CPU(struct rcu_data, rcu_sched_data);

-struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh);
+struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh, call_rcu_bh);
DEFINE_PER_CPU(struct rcu_data, rcu_bh_data);

static struct rcu_state *rcu_state;
@@ -2279,21 +2281,17 @@ 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));
+ struct rcu_state *rsp = type;

atomic_inc(&rcu_barrier_cpu_count);
- call_rcu_func = type;
- call_rcu_func(head, rcu_barrier_callback);
+ rsp->call(head, rcu_barrier_callback);
}

/*
* Orchestrate the specified type of RCU barrier, waiting for all
* RCU callbacks of the specified type to complete.
*/
-static void _rcu_barrier(struct rcu_state *rsp,
- void (*call_rcu_func)(struct rcu_head *head,
- void (*func)(struct rcu_head *head)))
+static void _rcu_barrier(struct rcu_state *rsp)
{
int cpu;
unsigned long flags;
@@ -2345,8 +2343,7 @@ static void _rcu_barrier(struct rcu_state *rsp,
while (cpu_is_offline(cpu) && ACCESS_ONCE(rdp->qlen))
schedule_timeout_interruptible(1);
} else if (ACCESS_ONCE(rdp->qlen)) {
- smp_call_function_single(cpu, rcu_barrier_func,
- (void *)call_rcu_func, 1);
+ smp_call_function_single(cpu, rcu_barrier_func, rsp, 1);
preempt_enable();
} else {
preempt_enable();
@@ -2367,7 +2364,7 @@ static void _rcu_barrier(struct rcu_state *rsp,
raw_spin_unlock_irqrestore(&rsp->onofflock, flags);
atomic_inc(&rcu_barrier_cpu_count);
smp_mb__after_atomic_inc(); /* Ensure atomic_inc() before callback. */
- call_rcu_func(&rh, rcu_barrier_callback);
+ rsp->call(&rh, rcu_barrier_callback);

/*
* Now that we have an rcu_barrier_callback() callback on each
@@ -2390,7 +2387,7 @@ static void _rcu_barrier(struct rcu_state *rsp,
*/
void rcu_barrier_bh(void)
{
- _rcu_barrier(&rcu_bh_state, call_rcu_bh);
+ _rcu_barrier(&rcu_bh_state);
}
EXPORT_SYMBOL_GPL(rcu_barrier_bh);

@@ -2399,7 +2396,7 @@ EXPORT_SYMBOL_GPL(rcu_barrier_bh);
*/
void rcu_barrier_sched(void)
{
- _rcu_barrier(&rcu_sched_state, call_rcu_sched);
+ _rcu_barrier(&rcu_sched_state);
}
EXPORT_SYMBOL_GPL(rcu_barrier_sched);

diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index df3c2c8..15837d7 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -350,6 +350,8 @@ struct rcu_state {
u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */
u8 levelspread[RCU_NUM_LVLS]; /* kids/node in each level. */
struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */
+ void (*call)(struct rcu_head *head, /* call_rcu() flavor. */
+ void (*func)(struct rcu_head *head));

/* The following fields are guarded by the root rcu_node's lock. */

diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 7cb86ae..6888706 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -78,7 +78,8 @@ static void __init rcu_bootup_announce_oddness(void)

#ifdef CONFIG_TREE_PREEMPT_RCU

-struct rcu_state rcu_preempt_state = RCU_STATE_INITIALIZER(rcu_preempt);
+struct rcu_state rcu_preempt_state =
+ RCU_STATE_INITIALIZER(rcu_preempt, call_rcu);
DEFINE_PER_CPU(struct rcu_data, rcu_preempt_data);
static struct rcu_state *rcu_state = &rcu_preempt_state;

@@ -944,7 +945,7 @@ static int rcu_preempt_cpu_has_callbacks(int cpu)
*/
void rcu_barrier(void)
{
- _rcu_barrier(&rcu_preempt_state, call_rcu);
+ _rcu_barrier(&rcu_preempt_state);
}
EXPORT_SYMBOL_GPL(rcu_barrier);

--
1.7.8


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