192 lines
5.0 KiB
C
192 lines
5.0 KiB
C
/*
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* Copyright (C) 2005-2014 Junjiro R. Okajima
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*
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* This program, aufs is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* simple read-write semaphore wrappers
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*/
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#ifndef __AUFS_RWSEM_H__
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#define __AUFS_RWSEM_H__
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#ifdef __KERNEL__
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#include "debug.h"
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struct au_rwsem {
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struct rw_semaphore rwsem;
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#ifdef CONFIG_AUFS_DEBUG
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/* just for debugging, not almighty counter */
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atomic_t rcnt, wcnt;
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#endif
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};
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#ifdef CONFIG_AUFS_DEBUG
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#define AuDbgCntInit(rw) do { \
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atomic_set(&(rw)->rcnt, 0); \
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atomic_set(&(rw)->wcnt, 0); \
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smp_mb(); /* atomic set */ \
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} while (0)
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#define AuDbgRcntInc(rw) atomic_inc(&(rw)->rcnt)
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#define AuDbgRcntDec(rw) WARN_ON(atomic_dec_return(&(rw)->rcnt) < 0)
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#define AuDbgWcntInc(rw) atomic_inc(&(rw)->wcnt)
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#define AuDbgWcntDec(rw) WARN_ON(atomic_dec_return(&(rw)->wcnt) < 0)
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#else
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#define AuDbgCntInit(rw) do {} while (0)
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#define AuDbgRcntInc(rw) do {} while (0)
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#define AuDbgRcntDec(rw) do {} while (0)
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#define AuDbgWcntInc(rw) do {} while (0)
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#define AuDbgWcntDec(rw) do {} while (0)
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#endif /* CONFIG_AUFS_DEBUG */
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/* to debug easier, do not make them inlined functions */
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#define AuRwMustNoWaiters(rw) AuDebugOn(!list_empty(&(rw)->rwsem.wait_list))
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/* rwsem_is_locked() is unusable */
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#define AuRwMustReadLock(rw) AuDebugOn(atomic_read(&(rw)->rcnt) <= 0)
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#define AuRwMustWriteLock(rw) AuDebugOn(atomic_read(&(rw)->wcnt) <= 0)
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#define AuRwMustAnyLock(rw) AuDebugOn(atomic_read(&(rw)->rcnt) <= 0 \
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&& atomic_read(&(rw)->wcnt) <= 0)
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#define AuRwDestroy(rw) AuDebugOn(atomic_read(&(rw)->rcnt) \
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|| atomic_read(&(rw)->wcnt))
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#define au_rw_class(rw, key) lockdep_set_class(&(rw)->rwsem, key)
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static inline void au_rw_init(struct au_rwsem *rw)
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{
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AuDbgCntInit(rw);
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init_rwsem(&rw->rwsem);
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}
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static inline void au_rw_init_wlock(struct au_rwsem *rw)
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{
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au_rw_init(rw);
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down_write(&rw->rwsem);
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AuDbgWcntInc(rw);
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}
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static inline void au_rw_init_wlock_nested(struct au_rwsem *rw,
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unsigned int lsc)
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{
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au_rw_init(rw);
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down_write_nested(&rw->rwsem, lsc);
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AuDbgWcntInc(rw);
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}
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static inline void au_rw_read_lock(struct au_rwsem *rw)
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{
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down_read(&rw->rwsem);
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AuDbgRcntInc(rw);
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}
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static inline void au_rw_read_lock_nested(struct au_rwsem *rw, unsigned int lsc)
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{
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down_read_nested(&rw->rwsem, lsc);
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AuDbgRcntInc(rw);
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}
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static inline void au_rw_read_unlock(struct au_rwsem *rw)
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{
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AuRwMustReadLock(rw);
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AuDbgRcntDec(rw);
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up_read(&rw->rwsem);
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}
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static inline void au_rw_dgrade_lock(struct au_rwsem *rw)
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{
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AuRwMustWriteLock(rw);
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AuDbgRcntInc(rw);
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AuDbgWcntDec(rw);
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downgrade_write(&rw->rwsem);
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}
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static inline void au_rw_write_lock(struct au_rwsem *rw)
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{
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down_write(&rw->rwsem);
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AuDbgWcntInc(rw);
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}
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static inline void au_rw_write_lock_nested(struct au_rwsem *rw,
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unsigned int lsc)
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{
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down_write_nested(&rw->rwsem, lsc);
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AuDbgWcntInc(rw);
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}
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static inline void au_rw_write_unlock(struct au_rwsem *rw)
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{
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AuRwMustWriteLock(rw);
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AuDbgWcntDec(rw);
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up_write(&rw->rwsem);
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}
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/* why is not _nested version defined */
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static inline int au_rw_read_trylock(struct au_rwsem *rw)
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{
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int ret;
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ret = down_read_trylock(&rw->rwsem);
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if (ret)
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AuDbgRcntInc(rw);
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return ret;
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}
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static inline int au_rw_write_trylock(struct au_rwsem *rw)
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{
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int ret;
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ret = down_write_trylock(&rw->rwsem);
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if (ret)
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AuDbgWcntInc(rw);
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return ret;
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}
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#undef AuDbgCntInit
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#undef AuDbgRcntInc
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#undef AuDbgRcntDec
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#undef AuDbgWcntInc
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#undef AuDbgWcntDec
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#define AuSimpleLockRwsemFuncs(prefix, param, rwsem) \
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static inline void prefix##_read_lock(param) \
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{ au_rw_read_lock(rwsem); } \
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static inline void prefix##_write_lock(param) \
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{ au_rw_write_lock(rwsem); } \
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static inline int prefix##_read_trylock(param) \
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{ return au_rw_read_trylock(rwsem); } \
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static inline int prefix##_write_trylock(param) \
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{ return au_rw_write_trylock(rwsem); }
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/* why is not _nested version defined */
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/* static inline void prefix##_read_trylock_nested(param, lsc)
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{ au_rw_read_trylock_nested(rwsem, lsc)); }
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static inline void prefix##_write_trylock_nestd(param, lsc)
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{ au_rw_write_trylock_nested(rwsem, lsc); } */
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#define AuSimpleUnlockRwsemFuncs(prefix, param, rwsem) \
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static inline void prefix##_read_unlock(param) \
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{ au_rw_read_unlock(rwsem); } \
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static inline void prefix##_write_unlock(param) \
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{ au_rw_write_unlock(rwsem); } \
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static inline void prefix##_downgrade_lock(param) \
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{ au_rw_dgrade_lock(rwsem); }
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#define AuSimpleRwsemFuncs(prefix, param, rwsem) \
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AuSimpleLockRwsemFuncs(prefix, param, rwsem) \
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AuSimpleUnlockRwsemFuncs(prefix, param, rwsem)
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#endif /* __KERNEL__ */
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#endif /* __AUFS_RWSEM_H__ */
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