From: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
The call_rcu_tasks_rude() and rcu_barrier_tasks_rude() APIs are currently
unused. This commit therefore removes their definitions and boot-time
self-tests.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@xxxxxxxxxx>
---
include/linux/rcupdate.h | 2 --
kernel/rcu/tasks.h | 55 +++++++++++++---------------------------
2 files changed, 17 insertions(+), 40 deletions(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 13f6f00aecf9..31e679c7110e 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -37,7 +37,6 @@
/* Exported common interfaces */
void call_rcu(struct rcu_head *head, rcu_callback_t func);
void rcu_barrier_tasks(void);
-void rcu_barrier_tasks_rude(void);
void synchronize_rcu(void);
struct rcu_gp_oldstate;
@@ -202,7 +201,6 @@ do { \
} while (0)
# ifdef CONFIG_TASKS_RUDE_RCU
-void call_rcu_tasks_rude(struct rcu_head *head, rcu_callback_t func);
void synchronize_rcu_tasks_rude(void);
# endif
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index ba3440a45b6d..4bc038bcc016 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -396,7 +396,7 @@ static void rcu_barrier_tasks_generic_cb(struct rcu_head *rhp)
// Wait for all in-flight callbacks for the specified RCU Tasks flavor.
// Operates in a manner similar to rcu_barrier().
-static void rcu_barrier_tasks_generic(struct rcu_tasks *rtp)
+static void __maybe_unused rcu_barrier_tasks_generic(struct rcu_tasks *rtp)
{
int cpu;
unsigned long flags;
@@ -1244,13 +1244,12 @@ void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
////////////////////////////////////////////////////////////////////////
//
-// "Rude" variant of Tasks RCU, inspired by Steve Rostedt's trick of
-// passing an empty function to schedule_on_each_cpu(). This approach
-// provides an asynchronous call_rcu_tasks_rude() API and batching of
-// concurrent calls to the synchronous synchronize_rcu_tasks_rude() API.
-// This invokes schedule_on_each_cpu() in order to send IPIs far and wide
-// and induces otherwise unnecessary context switches on all online CPUs,
-// whether idle or not.
+// "Rude" variant of Tasks RCU, inspired by Steve Rostedt's
+// trick of passing an empty function to schedule_on_each_cpu().
+// This approach provides batching of concurrent calls to the synchronous
+// synchronize_rcu_tasks_rude() API. This invokes schedule_on_each_cpu()
+// in order to send IPIs far and wide and induces otherwise unnecessary
+// context switches on all online CPUs, whether idle or not.
//
// Callback handling is provided by the rcu_tasks_kthread() function.
//
@@ -1268,11 +1267,11 @@ static void rcu_tasks_rude_wait_gp(struct rcu_tasks *rtp)
schedule_on_each_cpu(rcu_tasks_be_rude);
}
-void call_rcu_tasks_rude(struct rcu_head *rhp, rcu_callback_t func);
+static void call_rcu_tasks_rude(struct rcu_head *rhp, rcu_callback_t func);
DEFINE_RCU_TASKS(rcu_tasks_rude, rcu_tasks_rude_wait_gp, call_rcu_tasks_rude,
"RCU Tasks Rude");
-/**
+/*
* call_rcu_tasks_rude() - Queue a callback rude task-based grace period
* @rhp: structure to be used for queueing the RCU updates.
* @func: actual callback function to be invoked after the grace period
@@ -1289,12 +1288,14 @@ DEFINE_RCU_TASKS(rcu_tasks_rude, rcu_tasks_rude_wait_gp, call_rcu_tasks_rude,
*
* See the description of call_rcu() for more detailed information on
* memory ordering guarantees.
+ *
+ * This is no longer exported, and is instead reserved for use by
+ * synchronize_rcu_tasks_rude().
*/
-void call_rcu_tasks_rude(struct rcu_head *rhp, rcu_callback_t func)
+static void call_rcu_tasks_rude(struct rcu_head *rhp, rcu_callback_t func)
{
call_rcu_tasks_generic(rhp, func, &rcu_tasks_rude);
}
-EXPORT_SYMBOL_GPL(call_rcu_tasks_rude);
/**
* synchronize_rcu_tasks_rude - wait for a rude rcu-tasks grace period
@@ -1320,26 +1321,9 @@ void synchronize_rcu_tasks_rude(void)
}
EXPORT_SYMBOL_GPL(synchronize_rcu_tasks_rude);
-/**
- * rcu_barrier_tasks_rude - Wait for in-flight call_rcu_tasks_rude() callbacks.
- *
- * Although the current implementation is guaranteed to wait, it is not
- * obligated to, for example, if there are no pending callbacks.
- */
-void rcu_barrier_tasks_rude(void)
-{
- rcu_barrier_tasks_generic(&rcu_tasks_rude);
-}
-EXPORT_SYMBOL_GPL(rcu_barrier_tasks_rude);
-
-int rcu_tasks_rude_lazy_ms = -1;
-module_param(rcu_tasks_rude_lazy_ms, int, 0444);
-
static int __init rcu_spawn_tasks_rude_kthread(void)
{
rcu_tasks_rude.gp_sleep = HZ / 10;
- if (rcu_tasks_rude_lazy_ms >= 0)
- rcu_tasks_rude.lazy_jiffies = msecs_to_jiffies(rcu_tasks_rude_lazy_ms);
rcu_spawn_tasks_kthread_generic(&rcu_tasks_rude);
return 0;
}
@@ -2069,11 +2053,6 @@ static struct rcu_tasks_test_desc tests[] = {
/* If not defined, the test is skipped. */
.notrun = IS_ENABLED(CONFIG_TASKS_RCU),
},
- {
- .name = "call_rcu_tasks_rude()",
- /* If not defined, the test is skipped. */
- .notrun = IS_ENABLED(CONFIG_TASKS_RUDE_RCU),
- },
{
.name = "call_rcu_tasks_trace()",
/* If not defined, the test is skipped. */
@@ -2081,6 +2060,7 @@ static struct rcu_tasks_test_desc tests[] = {
}
};
+#if defined(CONFIG_TASKS_RCU) || defined(CONFIG_TASKS_TRACE_RCU)
static void test_rcu_tasks_callback(struct rcu_head *rhp)
{
struct rcu_tasks_test_desc *rttd =
@@ -2090,6 +2070,7 @@ static void test_rcu_tasks_callback(struct rcu_head *rhp)
rttd->notrun = false;
}
+#endif // #if defined(CONFIG_TASKS_RCU) || defined(CONFIG_TASKS_TRACE_RCU)
static void rcu_tasks_initiate_self_tests(void)
{
@@ -2102,16 +2083,14 @@ static void rcu_tasks_initiate_self_tests(void)
#ifdef CONFIG_TASKS_RUDE_RCU
pr_info("Running RCU Tasks Rude wait API self tests\n");
- tests[1].runstart = jiffies;
synchronize_rcu_tasks_rude();
- call_rcu_tasks_rude(&tests[1].rh, test_rcu_tasks_callback);
#endif
#ifdef CONFIG_TASKS_TRACE_RCU
pr_info("Running RCU Tasks Trace wait API self tests\n");
- tests[2].runstart = jiffies;
+ tests[1].runstart = jiffies;
synchronize_rcu_tasks_trace();
- call_rcu_tasks_trace(&tests[2].rh, test_rcu_tasks_callback);
+ call_rcu_tasks_trace(&tests[1].rh, test_rcu_tasks_callback);
#endif
}
--
2.40.1
