From 342a93247e0837101f27bbcca26f402902df98dc Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sun, 15 Aug 2021 23:28:23 +0200 Subject: [PATCH] locking/spinlock: Provide RT variant header: Provide the necessary wrappers around the actual rtmutex based spinlock implementation. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20210815211303.712897671@linutronix.de --- 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 diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index 5803b56..45310ea 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -312,8 +312,10 @@ static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock) 1 : ({ local_irq_restore(flags); 0; }); \ }) -/* Include rwlock functions */ +#ifndef CONFIG_PREEMPT_RT +/* Include rwlock functions for !RT */ #include +#endif /* * Pull the _spin_*()/_read_*()/_write_*() functions/declarations: @@ -324,6 +326,9 @@ static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock) # include #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_contended(spinlock_t *lock) #define assert_spin_locked(lock) assert_raw_spin_locked(&(lock)->rlock) +#else /* !CONFIG_PREEMPT_RT */ +# include +#endif /* CONFIG_PREEMPT_RT */ + /* * Pull the atomic_t declaration: * (asm-mips/atomic.h needs above definitions) diff --git a/include/linux/spinlock_api_smp.h b/include/linux/spinlock_api_smp.h index 19a9be9..6b8e1a0 100644 --- 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(raw_spinlock_t *lock) return 0; } +/* PREEMPT_RT has its own rwlock implementation */ +#ifndef CONFIG_PREEMPT_RT #include +#endif #endif /* __LINUX_SPINLOCK_API_SMP_H */ diff --git a/include/linux/spinlock_rt.h b/include/linux/spinlock_rt.h new file mode 100644 index 0000000..21228d3 --- /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 -- 2.7.4