summaryrefslogtreecommitdiff
path: root/fs/aufs/rwsem.h
diff options
context:
space:
mode:
Diffstat (limited to 'fs/aufs/rwsem.h')
-rw-r--r--fs/aufs/rwsem.h191
1 files changed, 191 insertions, 0 deletions
diff --git a/fs/aufs/rwsem.h b/fs/aufs/rwsem.h
new file mode 100644
index 000000000..deb813f3e
--- /dev/null
+++ b/fs/aufs/rwsem.h
@@ -0,0 +1,191 @@
+/*
+ * Copyright (C) 2005-2015 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_AUFS_DEBUG
+#define AuDbgCntInit(rw) do { \
+ atomic_set(&(rw)->rcnt, 0); \
+ atomic_set(&(rw)->wcnt, 0); \
+ smp_mb(); /* atomic set */ \
+} while (0)
+
+#define AuDbgRcntInc(rw) atomic_inc(&(rw)->rcnt)
+#define AuDbgRcntDec(rw) WARN_ON(atomic_dec_return(&(rw)->rcnt) < 0)
+#define AuDbgWcntInc(rw) atomic_inc(&(rw)->wcnt)
+#define AuDbgWcntDec(rw) WARN_ON(atomic_dec_return(&(rw)->wcnt) < 0)
+#else
+#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(!list_empty(&(rw)->rwsem.wait_list))
+/* rwsem_is_locked() is unusable */
+#define AuRwMustReadLock(rw) AuDebugOn(atomic_read(&(rw)->rcnt) <= 0)
+#define AuRwMustWriteLock(rw) AuDebugOn(atomic_read(&(rw)->wcnt) <= 0)
+#define AuRwMustAnyLock(rw) AuDebugOn(atomic_read(&(rw)->rcnt) <= 0 \
+ && atomic_read(&(rw)->wcnt) <= 0)
+#define AuRwDestroy(rw) AuDebugOn(atomic_read(&(rw)->rcnt) \
+ || atomic_read(&(rw)->wcnt))
+
+#define au_rw_class(rw, key) lockdep_set_class(&(rw)->rwsem, key)
+
+static inline void au_rw_init(struct au_rwsem *rw)
+{
+ AuDbgCntInit(rw);
+ init_rwsem(&rw->rwsem);
+}
+
+static inline void au_rw_init_wlock(struct au_rwsem *rw)
+{
+ au_rw_init(rw);
+ down_write(&rw->rwsem);
+ AuDbgWcntInc(rw);
+}
+
+static inline void au_rw_init_wlock_nested(struct au_rwsem *rw,
+ unsigned int lsc)
+{
+ au_rw_init(rw);
+ down_write_nested(&rw->rwsem, lsc);
+ AuDbgWcntInc(rw);
+}
+
+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 AuDbgCntInit
+#undef AuDbgRcntInc
+#undef AuDbgRcntDec
+#undef AuDbgWcntInc
+#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__ */