diff --git a/include/spl/sys/rwlock.h b/include/spl/sys/rwlock.h index 5e052b532a..89e02fa8f0 100644 --- a/include/spl/sys/rwlock.h +++ b/include/spl/sys/rwlock.h @@ -29,43 +29,6 @@ #include #include -/* Linux kernel compatibility */ -#if defined(CONFIG_PREEMPT_RT_FULL) -#define SPL_RWSEM_SINGLE_READER_VALUE (1) -#define SPL_RWSEM_SINGLE_WRITER_VALUE (0) -#elif defined(CONFIG_RWSEM_GENERIC_SPINLOCK) -#define SPL_RWSEM_SINGLE_READER_VALUE (1) -#define SPL_RWSEM_SINGLE_WRITER_VALUE (-1) -#elif defined(RWSEM_ACTIVE_MASK) -#define SPL_RWSEM_SINGLE_READER_VALUE (RWSEM_ACTIVE_READ_BIAS) -#define SPL_RWSEM_SINGLE_WRITER_VALUE (RWSEM_ACTIVE_WRITE_BIAS) -#endif - -/* Linux 3.16 changed activity to count for rwsem-spinlock */ -#if defined(CONFIG_PREEMPT_RT_FULL) -#define RWSEM_COUNT(sem) sem->read_depth -#elif defined(HAVE_RWSEM_ACTIVITY) -#define RWSEM_COUNT(sem) sem->activity -/* Linux 4.8 changed count to an atomic_long_t for !rwsem-spinlock */ -#elif defined(HAVE_RWSEM_ATOMIC_LONG_COUNT) -#define RWSEM_COUNT(sem) atomic_long_read(&(sem)->count) -#else -#define RWSEM_COUNT(sem) sem->count -#endif - -#if defined(RWSEM_SPINLOCK_IS_RAW) -#define spl_rwsem_lock_irqsave(lk, fl) raw_spin_lock_irqsave(lk, fl) -#define spl_rwsem_unlock_irqrestore(lk, fl) \ - raw_spin_unlock_irqrestore(lk, fl) -#define spl_rwsem_trylock_irqsave(lk, fl) raw_spin_trylock_irqsave(lk, fl) -#else -#define spl_rwsem_lock_irqsave(lk, fl) spin_lock_irqsave(lk, fl) -#define spl_rwsem_unlock_irqrestore(lk, fl) spin_unlock_irqrestore(lk, fl) -#define spl_rwsem_trylock_irqsave(lk, fl) spin_trylock_irqsave(lk, fl) -#endif /* RWSEM_SPINLOCK_IS_RAW */ - -#define spl_rwsem_is_locked(rwsem) rwsem_is_locked(rwsem) - typedef enum { RW_DRIVER = 2, RW_DEFAULT = 4, @@ -133,7 +96,7 @@ spl_rw_lockdep_on_maybe(krwlock_t *rwp) \ static inline int RW_LOCK_HELD(krwlock_t *rwp) { - return (spl_rwsem_is_locked(SEM(rwp))); + return (rwsem_is_locked(SEM(rwp))); } static inline int @@ -170,6 +133,12 @@ RW_READ_HELD(krwlock_t *rwp) */ #define rw_destroy(rwp) ((void) 0) +/* + * Upgrading a rwsem from a reader to a writer is not supported by the + * Linux kernel. The lock must be dropped and reacquired as a writer. + */ +#define rw_tryupgrade(rwp) RW_WRITE_HELD(rwp) + #define rw_tryenter(rwp, rw) \ ({ \ int _rc_ = 0; \ @@ -228,24 +197,9 @@ RW_READ_HELD(krwlock_t *rwp) spl_rw_lockdep_on_maybe(rwp); \ }) -#define rw_tryupgrade(rwp) \ -({ \ - int _rc_ = 0; \ - \ - if (RW_WRITE_HELD(rwp)) { \ - _rc_ = 1; \ - } else { \ - spl_rw_lockdep_off_maybe(rwp); \ - if ((_rc_ = rwsem_tryupgrade(SEM(rwp)))) \ - spl_rw_set_owner(rwp); \ - spl_rw_lockdep_on_maybe(rwp); \ - } \ - _rc_; \ -}) /* END CSTYLED */ int spl_rw_init(void); void spl_rw_fini(void); -int rwsem_tryupgrade(struct rw_semaphore *rwsem); #endif /* _SPL_RWLOCK_H */ diff --git a/module/spl/spl-rwlock.c b/module/spl/spl-rwlock.c index 886e16924e..10f7c38db4 100644 --- a/module/spl/spl-rwlock.c +++ b/module/spl/spl-rwlock.c @@ -24,106 +24,5 @@ * Solaris Porting Layer (SPL) Reader/Writer Lock Implementation. */ -#include -#include - -#if defined(CONFIG_PREEMPT_RT_FULL) - -#include -#define RT_MUTEX_OWNER_MASKALL 1UL - -static int -__rwsem_tryupgrade(struct rw_semaphore *rwsem) -{ -#if defined(READER_BIAS) && defined(WRITER_BIAS) - /* - * After the 4.9.20-rt16 kernel the realtime patch series lifted the - * single reader restriction. While this could be accommodated by - * adding additional compatibility code assume the rwsem can never - * be upgraded. All caller must already cleanly handle this case. - */ - return (0); -#else - ASSERT((struct task_struct *) - ((unsigned long)rwsem->lock.owner & ~RT_MUTEX_OWNER_MASKALL) == - current); - - /* - * Prior to 4.9.20-rt16 kernel the realtime patch series, rwsem is - * implemented as a single mutex held by readers and writers alike. - * However, this implementation would prevent a thread from taking - * a read lock twice, as the mutex would already be locked on - * the second attempt. Therefore the implementation allows a - * single thread to take a rwsem as read lock multiple times - * tracking that nesting as read_depth counter. - */ - if (rwsem->read_depth <= 1) { - /* - * In case, the current thread has not taken the lock - * more than once as read lock, we can allow an - * upgrade to a write lock. rwsem_rt.h implements - * write locks as read_depth == 0. - */ - rwsem->read_depth = 0; - return (1); - } - return (0); -#endif -} -#elif defined(CONFIG_RWSEM_GENERIC_SPINLOCK) -static int -__rwsem_tryupgrade(struct rw_semaphore *rwsem) -{ - int ret = 0; - unsigned long flags; - spl_rwsem_lock_irqsave(&rwsem->wait_lock, flags); - if (RWSEM_COUNT(rwsem) == SPL_RWSEM_SINGLE_READER_VALUE && - list_empty(&rwsem->wait_list)) { - ret = 1; - RWSEM_COUNT(rwsem) = SPL_RWSEM_SINGLE_WRITER_VALUE; - } - spl_rwsem_unlock_irqrestore(&rwsem->wait_lock, flags); - return (ret); -} -#elif defined(RWSEM_ACTIVE_MASK) -#if defined(HAVE_RWSEM_ATOMIC_LONG_COUNT) -static int -__rwsem_tryupgrade(struct rw_semaphore *rwsem) -{ - long val; - val = atomic_long_cmpxchg(&rwsem->count, SPL_RWSEM_SINGLE_READER_VALUE, - SPL_RWSEM_SINGLE_WRITER_VALUE); - return (val == SPL_RWSEM_SINGLE_READER_VALUE); -} -#else -static int -__rwsem_tryupgrade(struct rw_semaphore *rwsem) -{ - typeof(rwsem->count) val; - val = cmpxchg(&rwsem->count, SPL_RWSEM_SINGLE_READER_VALUE, - SPL_RWSEM_SINGLE_WRITER_VALUE); - return (val == SPL_RWSEM_SINGLE_READER_VALUE); -} -#endif -#else -static int -__rwsem_tryupgrade(struct rw_semaphore *rwsem) -{ - return (0); -} -#endif - -int -rwsem_tryupgrade(struct rw_semaphore *rwsem) -{ - if (__rwsem_tryupgrade(rwsem)) { - rwsem_release(&rwsem->dep_map, 1, _RET_IP_); - rwsem_acquire(&rwsem->dep_map, 0, 1, _RET_IP_); - return (1); - } - return (0); -} -EXPORT_SYMBOL(rwsem_tryupgrade); - int spl_rw_init(void) { return 0; } void spl_rw_fini(void) { }