On 2018-02-14 16:12:42 [-0600], Grygorii Strashko wrote:
> Hi All,
Hi,
> I can see below warning during boot on few TI boards am437x-idk, am335x-evm, am335x-ice
> All of them are non-SMP
I somehow missed the !SMP kernel… What about this:
Subject: [PATCH] RCU: skip the "schedule() in RCU section" warning on UP, too
In "RCU: we need to skip that warning but only on sleeping locks" we
skipped a warning on SMP systems in case we schedule out in a RCU
section while attempt to obtain a sleeping lock. This is also required
on UP systems.
In order to do so, I introduce a tiny version of migrate_disable() +
_enable() which only update the counters which we then can check against
on RT && !SMP.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
include/linux/preempt.h | 9 +++++++++
include/linux/sched.h | 6 ++++++
kernel/rcu/tree_plugin.h | 2 +-
kernel/sched/core.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 61 insertions(+), 1 deletion(-)
diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index b0e6248c8a3c..0591df500e9d 100644
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -231,6 +231,15 @@ extern void migrate_enable(void);
int __migrate_disabled(struct task_struct *p);
+#elif !defined(CONFIG_SMP) && defined(CONFIG_PREEMPT_RT_BASE)
+
+extern void migrate_disable(void);
+extern void migrate_enable(void);
+static inline int __migrate_disabled(struct task_struct *p)
+{
+ return 0;
+}
+
#else
#define migrate_disable() barrier()
#define migrate_enable() barrier()
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 33bedd733d00..9a8974fcb95c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -593,6 +593,12 @@ struct task_struct {
# ifdef CONFIG_SCHED_DEBUG
int migrate_disable_atomic;
# endif
+
+#elif !defined(CONFIG_SMP) && defined(CONFIG_PREEMPT_RT_BASE)
+ int migrate_disable;
+# ifdef CONFIG_SCHED_DEBUG
+ int migrate_disable_atomic;
+# endif
#endif
#ifdef CONFIG_PREEMPT_RCU
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 36e44ecd576e..3315ebad932f 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -304,7 +304,7 @@ static void rcu_preempt_note_context_switch(bool preempt)
int mg_counter = 0;
RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_preempt_note_context_switch() invoked with interrupts enabled!!!\n");
-#if defined(CONFIG_PREEMPT_COUNT) && defined(CONFIG_SMP)
+#if defined(CONFIG_PREEMPT_RT_BASE)
mg_counter = t->migrate_disable;
#endif
WARN_ON_ONCE(!preempt && t->rcu_read_lock_nesting > 0 && !mg_counter);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1ab422da7706..ea8bfeddcea0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7047,4 +7047,49 @@ void migrate_enable(void)
preempt_enable();
}
EXPORT_SYMBOL(migrate_enable);
+
+#elif !defined(CONFIG_SMP) && defined(CONFIG_PREEMPT_RT_BASE)
+void migrate_disable(void)
+{
+ struct task_struct *p = current;
+
+ if (in_atomic() || irqs_disabled()) {
+#ifdef CONFIG_SCHED_DEBUG
+ p->migrate_disable_atomic++;
+#endif
+ return;
+ }
+#ifdef CONFIG_SCHED_DEBUG
+ if (unlikely(p->migrate_disable_atomic)) {
+ tracing_off();
+ WARN_ON_ONCE(1);
+ }
+#endif
+
+ p->migrate_disable++;
+}
+EXPORT_SYMBOL(migrate_disable);
+
+void migrate_enable(void)
+{
+ struct task_struct *p = current;
+
+ if (in_atomic() || irqs_disabled()) {
+#ifdef CONFIG_SCHED_DEBUG
+ p->migrate_disable_atomic--;
+#endif
+ return;
+ }
+
+#ifdef CONFIG_SCHED_DEBUG
+ if (unlikely(p->migrate_disable_atomic)) {
+ tracing_off();
+ WARN_ON_ONCE(1);
+ }
+#endif
+
+ WARN_ON_ONCE(p->migrate_disable <= 0);
+ p->migrate_disable--;
+}
+EXPORT_SYMBOL(migrate_enable);
#endif
--
2.16.1
Sebastian
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