[patch V4 29/68] locking/spinlock: Provide RT variant header

Thomas Gleixner
2021-08-11T12:24:49Z

Provide the necessary wrappers around the actual rtmutex based spinlock
implementation.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
V4: spin_unlock() -> rt_spin_unlock() (Peter)
---
include/linux/spinlock.h | 11 ++
include/linux/spinlock_api_smp.h | 3
include/linux/spinlock_rt.h | 149 +++++++++++++++++++++++++++++++++++++++
3 files changed, 162 insertions(+), 1 deletion(-)
create mode 100644 include/linux/spinlock_rt.h
---
--- a/include/linux/spinlock.h
+++ b/include/linux/spinlock.h
@@ -312,8 +312,10 @@ static inline void do_raw_spin_unlock(ra
1 : ({ local_irq_restore(flags); 0; }); \
})

-/* Include rwlock functions */
+#ifndef CONFIG_PREEMPT_RT
+/* Include rwlock functions for !RT */
#include <linux/rwlock.h>
+#endif

/*
* Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
@@ -324,6 +326,9 @@ static inline void do_raw_spin_unlock(ra
# include <linux/spinlock_api_up.h>
#endif

+/* Non PREEMPT_RT kernel map to raw spinlocks */
+#ifndef CONFIG_PREEMPT_RT
+
/*
* Map the spin_lock functions to the raw variants for PREEMPT_RT=n
*/
@@ -458,6 +463,10 @@ static __always_inline int spin_is_conte

#define assert_spin_locked(lock) assert_raw_spin_locked(&(lock)->rlock)

+#else /* !CONFIG_PREEMPT_RT */
+# include <linux/spinlock_rt.h>
+#endif /* CONFIG_PREEMPT_RT */
+
/*
* Pull the atomic_t declaration:
* (asm-mips/atomic.h needs above definitions)
--- a/include/linux/spinlock_api_smp.h
+++ b/include/linux/spinlock_api_smp.h
@@ -187,6 +187,9 @@ static inline int __raw_spin_trylock_bh(
return 0;
}

+/* PREEMPT_RT has it's own rwlock implementation */
+#ifndef CONFIG_PREEMPT_RT
#include <linux/rwlock_api_smp.h>
+#endif

#endif /* __LINUX_SPINLOCK_API_SMP_H */
--- /dev/null
+++ b/include/linux/spinlock_rt.h
@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#ifndef __LINUX_SPINLOCK_RT_H
+#define __LINUX_SPINLOCK_RT_H
+
+#ifndef __LINUX_SPINLOCK_H
+#error Do not include directly. Use spinlock.h
+#endif
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+extern void __rt_spin_lock_init(spinlock_t *lock, const char *name,
+ struct lock_class_key *key);
+#else
+static inline void __rt_spin_lock_init(spinlock_t *lock, const char *name,
+ struct lock_class_key *key)
+{
+}
+#endif
+
+#define spin_lock_init(slock) \
+do { \
+ static struct lock_class_key __key; \
+ \
+ rt_mutex_base_init(&(slock)->lock); \
+ __rt_spin_lock_init(slock, #slock, &__key); \
+} while (0)
+
+extern void rt_spin_lock(spinlock_t *lock);
+extern void rt_spin_lock_nested(spinlock_t *lock, int subclass);
+extern void rt_spin_lock_nest_lock(spinlock_t *lock, struct lockdep_map *nest_lock);
+extern void rt_spin_unlock(spinlock_t *lock);
+extern void rt_spin_lock_unlock(spinlock_t *lock);
+extern int rt_spin_trylock_bh(spinlock_t *lock);
+extern int rt_spin_trylock(spinlock_t *lock);
+
+static __always_inline void spin_lock(spinlock_t *lock)
+{
+ rt_spin_lock(lock);
+}
+
+#ifdef CONFIG_LOCKDEP
+# define __spin_lock_nested(lock, subclass) \
+ rt_spin_lock_nested(lock, subclass)
+
+# define __spin_lock_nest_lock(lock, nest_lock) \
+ do { \
+ typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
+ rt_spin_lock_nest_lock(lock, &(nest_lock)->dep_map); \
+ } while (0)
+# define __spin_lock_irqsave_nested(lock, flags, subclass) \
+ do { \
+ typecheck(unsigned long, flags); \
+ flags = 0; \
+ __spin_lock_nested(lock, subclass); \
+ } while (0)
+
+#else
+ /*
+ * Always evaluate the 'subclass' argument to avoid that the compiler
+ * warns about set-but-not-used variables when building with
+ * CONFIG_DEBUG_LOCK_ALLOC=n and with W=1.
+ */
+# define __spin_lock_nested(lock, subclass) spin_lock(((void)(subclass), (lock)))
+# define __spin_lock_nest_lock(lock, subclass) spin_lock(((void)(subclass), (lock)))
+# define __spin_lock_irqsave_nested(lock, flags, subclass) \
+ spin_lock_irqsave(((void)(subclass), (lock)), flags)
+#endif
+
+#define spin_lock_nested(lock, subclass) \
+ __spin_lock_nested(lock, subclass)
+
+#define spin_lock_nest_lock(lock, nest_lock) \
+ __spin_lock_nest_lock(lock, nest_lock)
+
+#define spin_lock_irqsave_nested(lock, flags, subclass) \
+ __spin_lock_irqsave_nested(lock, flags, subclass)
+
+static __always_inline void spin_lock_bh(spinlock_t *lock)
+{
+ /* Investigate: Drop bh when blocking ? */
+ local_bh_disable();
+ rt_spin_lock(lock);
+}
+
+static __always_inline void spin_lock_irq(spinlock_t *lock)
+{
+ rt_spin_lock(lock);
+}
+
+#define spin_lock_irqsave(lock, flags) \
+ do { \
+ typecheck(unsigned long, flags); \
+ flags = 0; \
+ spin_lock(lock); \
+ } while (0)
+
+static __always_inline void spin_unlock(spinlock_t *lock)
+{
+ rt_spin_unlock(lock);
+}
+
+static __always_inline void spin_unlock_bh(spinlock_t *lock)
+{
+ rt_spin_unlock(lock);
+ local_bh_enable();
+}
+
+static __always_inline void spin_unlock_irq(spinlock_t *lock)
+{
+ rt_spin_unlock(lock);
+}
+
+static __always_inline void spin_unlock_irqrestore(spinlock_t *lock,
+ unsigned long flags)
+{
+ rt_spin_unlock(lock);
+}
+
+#define spin_trylock(lock) \
+ __cond_lock(lock, rt_spin_trylock(lock))
+
+#define spin_trylock_bh(lock) \
+ __cond_lock(lock, rt_spin_trylock_bh(lock))
+
+#define spin_trylock_irq(lock) \
+ __cond_lock(lock, rt_spin_trylock(lock))
+
+#define __spin_trylock_irqsave(lock, flags) \
+({ \
+ int __locked; \
+ \
+ typecheck(unsigned long, flags); \
+ flags = 0; \
+ __locked = spin_trylock(lock); \
+ __locked; \
+})
+
+#define spin_trylock_irqsave(lock, flags) \
+ __cond_lock(lock, __spin_trylock_irqsave(lock, flags))
+
+#define spin_is_contended(lock) (((void)(lock), 0))
+
+static inline int spin_is_locked(spinlock_t *lock)
+{
+ return rt_mutex_base_is_locked(&lock->lock);
+}
+
+#define assert_spin_locked(lock) BUG_ON(!spin_is_locked(lock))
+
+#endif