lkml.org 
[lkml]   [2018]   [Aug]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH tip/core/rcu 23/24] rcu: Define rcu_all_qs() only in !PREEMPT builds
Date
Now that rcu_all_qs() is used only in !PREEMPT builds, move it to
tree_plugin.h so that it is defined only in those builds. This in
turn means that rcu_momentary_dyntick_idle() is only used in !PREEMPT
builds, but it is simply marked __maybe_unused in order to keep it
near the rest of the dyntick-idle code.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
include/linux/rcutree.h | 2 ++
kernel/rcu/tree.c | 41 +---------------------------------------
kernel/rcu/tree_plugin.h | 39 ++++++++++++++++++++++++++++++++++++++
3 files changed, 42 insertions(+), 40 deletions(-)

diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index d09a9abe9440..7f83179177d1 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -66,7 +66,9 @@ void rcu_scheduler_starting(void);
extern int rcu_scheduler_active __read_mostly;
void rcu_end_inkernel_boot(void);
bool rcu_is_watching(void);
+#ifndef CONFIG_PREEMPT
void rcu_all_qs(void);
+#endif

/* RCUtree hotplug events */
int rcutree_prepare_cpu(unsigned int cpu);
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index e8fbb7ee76cc..5f2a12a65b42 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -356,7 +356,7 @@ bool rcu_eqs_special_set(int cpu)
*
* The caller must have disabled interrupts and must not be idle.
*/
-static void rcu_momentary_dyntick_idle(void)
+static void __maybe_unused rcu_momentary_dyntick_idle(void)
{
struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
int special;
@@ -381,45 +381,6 @@ static int rcu_is_cpu_rrupt_from_idle(void)
__this_cpu_read(rcu_dynticks.dynticks_nmi_nesting) <= 1;
}

-/*
- * Register an urgently needed quiescent state. If there is an
- * emergency, invoke rcu_momentary_dyntick_idle() to do a heavy-weight
- * dyntick-idle quiescent state visible to other CPUs, which will in
- * some cases serve for expedited as well as normal grace periods.
- * Either way, register a lightweight quiescent state.
- *
- * The barrier() calls are redundant in the common case when this is
- * called externally, but just in case this is called from within this
- * file.
- *
- */
-void rcu_all_qs(void)
-{
- unsigned long flags;
-
- if (!raw_cpu_read(rcu_dynticks.rcu_urgent_qs))
- return;
- preempt_disable();
- /* Load rcu_urgent_qs before other flags. */
- if (!smp_load_acquire(this_cpu_ptr(&rcu_dynticks.rcu_urgent_qs))) {
- preempt_enable();
- return;
- }
- this_cpu_write(rcu_dynticks.rcu_urgent_qs, false);
- barrier(); /* Avoid RCU read-side critical sections leaking down. */
- if (unlikely(raw_cpu_read(rcu_dynticks.rcu_need_heavy_qs))) {
- local_irq_save(flags);
- rcu_momentary_dyntick_idle();
- local_irq_restore(flags);
- }
- if (unlikely(raw_cpu_read(rcu_data.cpu_no_qs.b.exp)))
- rcu_qs();
- this_cpu_inc(rcu_dynticks.rcu_qs_ctr);
- barrier(); /* Avoid RCU read-side critical sections leaking up. */
- preempt_enable();
-}
-EXPORT_SYMBOL_GPL(rcu_all_qs);
-
#define DEFAULT_RCU_BLIMIT 10 /* Maximum callbacks per rcu_do_batch. */
static long blimit = DEFAULT_RCU_BLIMIT;
#define DEFAULT_RCU_QHIMARK 10000 /* If this many pending, ignore blimit. */
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index cd4c1b979446..7add1c297500 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -947,6 +947,45 @@ static void rcu_qs(void)
rcu_report_exp_rdp(this_cpu_ptr(&rcu_data));
}

+/*
+ * Register an urgently needed quiescent state. If there is an
+ * emergency, invoke rcu_momentary_dyntick_idle() to do a heavy-weight
+ * dyntick-idle quiescent state visible to other CPUs, which will in
+ * some cases serve for expedited as well as normal grace periods.
+ * Either way, register a lightweight quiescent state.
+ *
+ * The barrier() calls are redundant in the common case when this is
+ * called externally, but just in case this is called from within this
+ * file.
+ *
+ */
+void rcu_all_qs(void)
+{
+ unsigned long flags;
+
+ if (!raw_cpu_read(rcu_dynticks.rcu_urgent_qs))
+ return;
+ preempt_disable();
+ /* Load rcu_urgent_qs before other flags. */
+ if (!smp_load_acquire(this_cpu_ptr(&rcu_dynticks.rcu_urgent_qs))) {
+ preempt_enable();
+ return;
+ }
+ this_cpu_write(rcu_dynticks.rcu_urgent_qs, false);
+ barrier(); /* Avoid RCU read-side critical sections leaking down. */
+ if (unlikely(raw_cpu_read(rcu_dynticks.rcu_need_heavy_qs))) {
+ local_irq_save(flags);
+ rcu_momentary_dyntick_idle();
+ local_irq_restore(flags);
+ }
+ if (unlikely(raw_cpu_read(rcu_data.cpu_no_qs.b.exp)))
+ rcu_qs();
+ this_cpu_inc(rcu_dynticks.rcu_qs_ctr);
+ barrier(); /* Avoid RCU read-side critical sections leaking up. */
+ preempt_enable();
+}
+EXPORT_SYMBOL_GPL(rcu_all_qs);
+
/*
* Note a PREEMPT=n context switch. The caller must have disabled interrupts.
*/
--
2.17.1
\
 
 \ /
  Last update: 2018-08-30 00:54    [W:0.155 / U:1.328 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site