[patch V3 28/64] locking/spinlock: Provide RT specific spinlock type

Thomas Gleixner
2021-08-05T15:43:33Z

From: Thomas Gleixner <tglx@linutronix.de>

RT replaces spinlocks with a simple wrapper around a rtmutex which turns
spinlocks on RT into 'sleeping' spinlocks. The actual implementation of the
spinlock API differs from a regular rtmutex as it does neither handle
timeouts nor signals and it is state preserving across the lock operation.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/spinlock_types.h | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
---
--- a/include/linux/spinlock_types.h
+++ b/include/linux/spinlock_types.h
@@ -11,6 +11,9 @@

#include <linux/spinlock_types_raw.h>

+#ifndef CONFIG_PREEMPT_RT
+
+/* Non PREEMPT_RT kernels map spinlock to raw_spinlock */
typedef struct spinlock {
union {
struct raw_spinlock rlock;
@@ -39,6 +42,29 @@ typedef struct spinlock {

#define DEFINE_SPINLOCK(x) spinlock_t x = __SPIN_LOCK_UNLOCKED(x)

+#else /* !CONFIG_PREEMPT_RT */
+
+/* PREEMPT_RT kernels map spinlock to rt_mutex */
+#include <linux/rtmutex.h>
+
+typedef struct spinlock {
+ struct rt_mutex_base lock;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+ struct lockdep_map dep_map;
+#endif
+} spinlock_t;
+
+#define __SPIN_LOCK_UNLOCKED(name) \
+ { \
+ .lock = __RT_MUTEX_BASE_INITIALIZER(name.lock), \
+ SPIN_DEP_MAP_INIT(name) \
+ }
+
+#define DEFINE_SPINLOCK(name) \
+ spinlock_t name = __SPIN_LOCK_UNLOCKED(name)
+
+#endif /* CONFIG_PREEMPT_RT */
+
#include <linux/rwlock_types.h>

#endif /* __LINUX_SPINLOCK_TYPES_H */