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From: Mike Galbraith <umgwanakikbuti@gmail.com>
Date: Fri, 2 May 2014 13:13:22 +0200
Subject: stomp-machine: create lg_global_trylock_relax() primitive
Create lg_global_trylock_relax() for use by stopper thread when it cannot
schedule, to deal with stop_cpus_lock, which is now an lglock.
Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
include/linux/lglock.h | 6 ++++++
include/linux/spinlock_rt.h | 1 +
kernel/locking/lglock.c | 25 +++++++++++++++++++++++++
kernel/locking/rtmutex.c | 5 +++++
4 files changed, 37 insertions(+)
--- a/include/linux/lglock.h
+++ b/include/linux/lglock.h
@@ -82,6 +82,12 @@ void lg_double_unlock(struct lglock *lg,
void lg_global_lock(struct lglock *lg);
void lg_global_unlock(struct lglock *lg);
+#ifndef CONFIG_PREEMPT_RT_FULL
+#define lg_global_trylock_relax(name) lg_global_lock(name)
+#else
+void lg_global_trylock_relax(struct lglock *lg);
+#endif
+
#else
/* When !CONFIG_SMP, map lglock to spinlock */
#define lglock spinlock
--- a/include/linux/spinlock_rt.h
+++ b/include/linux/spinlock_rt.h
@@ -34,6 +34,7 @@ extern int atomic_dec_and_spin_lock(atom
*/
extern void __lockfunc __rt_spin_lock(struct rt_mutex *lock);
extern void __lockfunc __rt_spin_unlock(struct rt_mutex *lock);
+extern int __lockfunc __rt_spin_trylock(struct rt_mutex *lock);
#define spin_lock(lock) \
do { \
--- a/kernel/locking/lglock.c
+++ b/kernel/locking/lglock.c
@@ -127,3 +127,28 @@ void lg_global_unlock(struct lglock *lg)
preempt_enable_nort();
}
EXPORT_SYMBOL(lg_global_unlock);
+
+#ifdef CONFIG_PREEMPT_RT_FULL
+/*
+ * HACK: If you use this, you get to keep the pieces.
+ * Used in queue_stop_cpus_work() when stop machinery
+ * is called from inactive CPU, so we can't schedule.
+ */
+# define lg_do_trylock_relax(l) \
+ do { \
+ while (!__rt_spin_trylock(l)) \
+ cpu_relax(); \
+ } while (0)
+
+void lg_global_trylock_relax(struct lglock *lg)
+{
+ int i;
+
+ lock_acquire_exclusive(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
+ for_each_possible_cpu(i) {
+ lg_lock_ptr *lock;
+ lock = per_cpu_ptr(lg->lock, i);
+ lg_do_trylock_relax(lock);
+ }
+}
+#endif
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1153,6 +1153,11 @@ void __lockfunc rt_spin_unlock_wait(spin
}
EXPORT_SYMBOL(rt_spin_unlock_wait);
+int __lockfunc __rt_spin_trylock(struct rt_mutex *lock)
+{
+ return rt_mutex_trylock(lock);
+}
+
int __lockfunc rt_spin_trylock(spinlock_t *lock)
{
int ret = rt_mutex_trylock(&lock->lock);
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