diff options
Diffstat (limited to 'fs/aufs/rwsem.h')
| -rw-r--r-- | fs/aufs/rwsem.h | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/fs/aufs/rwsem.h b/fs/aufs/rwsem.h new file mode 100644 index 000000000000..2abe89fb29ff --- /dev/null +++ b/fs/aufs/rwsem.h @@ -0,0 +1,198 @@ +/* + * Copyright (C) 2005-2017 Junjiro R. Okajima + * + * This program, aufs is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +/* + * simple read-write semaphore wrappers + */ + +#ifndef __AUFS_RWSEM_H__ +#define __AUFS_RWSEM_H__ + +#ifdef __KERNEL__ + +#include "debug.h" + +struct au_rwsem { + struct rw_semaphore rwsem; +#ifdef CONFIG_AUFS_DEBUG + /* just for debugging, not almighty counter */ + atomic_t rcnt, wcnt; +#endif +}; + +#ifdef CONFIG_LOCKDEP +#define au_lockdep_set_name(rw) \ + lockdep_set_class_and_name(&(rw)->rwsem, \ + /*original key*/(rw)->rwsem.dep_map.key, \ + /*name*/#rw) +#else +#define au_lockdep_set_name(rw) do {} while (0) +#endif + +#ifdef CONFIG_AUFS_DEBUG +#define AuDbgCntInit(rw) do { \ + atomic_set(&(rw)->rcnt, 0); \ + atomic_set(&(rw)->wcnt, 0); \ + smp_mb(); /* atomic set */ \ +} while (0) + +#define AuDbgCnt(rw, cnt) atomic_read(&(rw)->cnt) +#define AuDbgCntInc(rw, cnt) atomic_inc(&(rw)->cnt) +#define AuDbgCntDec(rw, cnt) WARN_ON(atomic_dec_return(&(rw)->cnt) < 0) +#define AuDbgRcntInc(rw) AuDbgCntInc(rw, rcnt) +#define AuDbgRcntDec(rw) AuDbgCntDec(rw, rcnt) +#define AuDbgWcntInc(rw) AuDbgCntInc(rw, wcnt) +#define AuDbgWcntDec(rw) AuDbgCntDec(rw, wcnt) +#else +#define AuDbgCnt(rw, cnt) 0 +#define AuDbgCntInit(rw) do {} while (0) +#define AuDbgRcntInc(rw) do {} while (0) +#define AuDbgRcntDec(rw) do {} while (0) +#define AuDbgWcntInc(rw) do {} while (0) +#define AuDbgWcntDec(rw) do {} while (0) +#endif /* CONFIG_AUFS_DEBUG */ + +/* to debug easier, do not make them inlined functions */ +#define AuRwMustNoWaiters(rw) AuDebugOn(rwsem_is_contended(&(rw)->rwsem)) +/* rwsem_is_locked() is unusable */ +#define AuRwMustReadLock(rw) AuDebugOn(AuDbgCnt(rw, rcnt) <= 0) +#define AuRwMustWriteLock(rw) AuDebugOn(AuDbgCnt(rw, wcnt) <= 0) +#define AuRwMustAnyLock(rw) AuDebugOn(AuDbgCnt(rw, rcnt) <= 0 \ + && AuDbgCnt(rw, wcnt) <= 0) +#define AuRwDestroy(rw) AuDebugOn(AuDbgCnt(rw, rcnt) \ + || AuDbgCnt(rw, wcnt)) + +#define au_rw_init(rw) do { \ + AuDbgCntInit(rw); \ + init_rwsem(&(rw)->rwsem); \ + au_lockdep_set_name(rw); \ + } while (0) + +#define au_rw_init_wlock(rw) do { \ + au_rw_init(rw); \ + down_write(&(rw)->rwsem); \ + AuDbgWcntInc(rw); \ + } while (0) + +#define au_rw_init_wlock_nested(rw, lsc) do { \ + au_rw_init(rw); \ + down_write_nested(&(rw)->rwsem, lsc); \ + AuDbgWcntInc(rw); \ + } while (0) + +static inline void au_rw_read_lock(struct au_rwsem *rw) +{ + down_read(&rw->rwsem); + AuDbgRcntInc(rw); +} + +static inline void au_rw_read_lock_nested(struct au_rwsem *rw, unsigned int lsc) +{ + down_read_nested(&rw->rwsem, lsc); + AuDbgRcntInc(rw); +} + +static inline void au_rw_read_unlock(struct au_rwsem *rw) +{ + AuRwMustReadLock(rw); + AuDbgRcntDec(rw); + up_read(&rw->rwsem); +} + +static inline void au_rw_dgrade_lock(struct au_rwsem *rw) +{ + AuRwMustWriteLock(rw); + AuDbgRcntInc(rw); + AuDbgWcntDec(rw); + downgrade_write(&rw->rwsem); +} + +static inline void au_rw_write_lock(struct au_rwsem *rw) +{ + down_write(&rw->rwsem); + AuDbgWcntInc(rw); +} + +static inline void au_rw_write_lock_nested(struct au_rwsem *rw, + unsigned int lsc) +{ + down_write_nested(&rw->rwsem, lsc); + AuDbgWcntInc(rw); +} + +static inline void au_rw_write_unlock(struct au_rwsem *rw) +{ + AuRwMustWriteLock(rw); + AuDbgWcntDec(rw); + up_write(&rw->rwsem); +} + +/* why is not _nested version defined */ +static inline int au_rw_read_trylock(struct au_rwsem *rw) +{ + int ret; + + ret = down_read_trylock(&rw->rwsem); + if (ret) + AuDbgRcntInc(rw); + return ret; +} + +static inline int au_rw_write_trylock(struct au_rwsem *rw) +{ + int ret; + + ret = down_write_trylock(&rw->rwsem); + if (ret) + AuDbgWcntInc(rw); + return ret; +} + +#undef AuDbgCntDec +#undef AuDbgRcntInc +#undef AuDbgRcntDec +#undef AuDbgWcntDec + +#define AuSimpleLockRwsemFuncs(prefix, param, rwsem) \ +static inline void prefix##_read_lock(param) \ +{ au_rw_read_lock(rwsem); } \ +static inline void prefix##_write_lock(param) \ +{ au_rw_write_lock(rwsem); } \ +static inline int prefix##_read_trylock(param) \ +{ return au_rw_read_trylock(rwsem); } \ +static inline int prefix##_write_trylock(param) \ +{ return au_rw_write_trylock(rwsem); } +/* why is not _nested version defined */ +/* static inline void prefix##_read_trylock_nested(param, lsc) +{ au_rw_read_trylock_nested(rwsem, lsc)); } +static inline void prefix##_write_trylock_nestd(param, lsc) +{ au_rw_write_trylock_nested(rwsem, lsc); } */ + +#define AuSimpleUnlockRwsemFuncs(prefix, param, rwsem) \ +static inline void prefix##_read_unlock(param) \ +{ au_rw_read_unlock(rwsem); } \ +static inline void prefix##_write_unlock(param) \ +{ au_rw_write_unlock(rwsem); } \ +static inline void prefix##_downgrade_lock(param) \ +{ au_rw_dgrade_lock(rwsem); } + +#define AuSimpleRwsemFuncs(prefix, param, rwsem) \ + AuSimpleLockRwsemFuncs(prefix, param, rwsem) \ + AuSimpleUnlockRwsemFuncs(prefix, param, rwsem) + +#endif /* __KERNEL__ */ +#endif /* __AUFS_RWSEM_H__ */ |