From 026659b9774e4c586baeb457557fcfc4e0ad144b Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Sun, 15 Aug 2021 23:29:28 +0200
Subject: [PATCH] locking/local_lock: Add PREEMPT_RT support
Git-commit: 026659b9774e4c586baeb457557fcfc4e0ad144b
Patch-mainline: v5.15-rc1
References: bsc#1190137 bsc#1189998

On PREEMPT_RT enabled kernels local_lock maps to a per CPU 'sleeping'
spinlock which protects the critical section while staying preemptible. CPU
locality is established by disabling migration.

Provide the necessary types and macros to substitute the non-RT variant.

Co-developed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211306.023630962@linutronix.de
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>

---
 include/linux/local_lock_internal.h | 44 +++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/include/linux/local_lock_internal.h b/include/linux/local_lock_internal.h
index 3f02b818625e..975e33b793a7 100644
--- a/include/linux/local_lock_internal.h
+++ b/include/linux/local_lock_internal.h
@@ -6,6 +6,8 @@
 #include <linux/percpu-defs.h>
 #include <linux/lockdep.h>
 
+#ifndef CONFIG_PREEMPT_RT
+
 typedef struct {
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 	struct lockdep_map	dep_map;
@@ -95,3 +97,45 @@ do {								\
 		local_lock_release(this_cpu_ptr(lock));		\
 		local_irq_restore(flags);			\
 	} while (0)
+
+#else /* !CONFIG_PREEMPT_RT */
+
+/*
+ * On PREEMPT_RT local_lock maps to a per CPU spinlock, which protects the
+ * critical section while staying preemptible.
+ */
+typedef spinlock_t local_lock_t;
+
+#define INIT_LOCAL_LOCK(lockname) __LOCAL_SPIN_LOCK_UNLOCKED((lockname))
+
+#define __local_lock_init(l)					\
+	do {							\
+		local_spin_lock_init((l));			\
+	} while (0)
+
+#define __local_lock(__lock)					\
+	do {							\
+		migrate_disable();				\
+		spin_lock(this_cpu_ptr((__lock)));		\
+	} while (0)
+
+#define __local_lock_irq(lock)			__local_lock(lock)
+
+#define __local_lock_irqsave(lock, flags)			\
+	do {							\
+		typecheck(unsigned long, flags);		\
+		flags = 0;					\
+		__local_lock(lock);				\
+	} while (0)
+
+#define __local_unlock(__lock)					\
+	do {							\
+		spin_unlock(this_cpu_ptr((__lock)));		\
+		migrate_enable();				\
+	} while (0)
+
+#define __local_unlock_irq(lock)		__local_unlock(lock)
+
+#define __local_unlock_irqrestore(lock, flags)	__local_unlock(lock)
+
+#endif /* CONFIG_PREEMPT_RT */
-- 
2.26.2