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git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-11-01 09:13:37 +00:00
f44cc269a1
We were grabbing the sequence number before unlock incremented it - fix this by moving the increment to seqmutex_lock() (so the seqmutex_relock() failure path skips the mutex_trylock()), and returning the sequence number from unlock(), to make the API simpler and safer. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
45 lines
825 B
C
45 lines
825 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _BCACHEFS_SEQMUTEX_H
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#define _BCACHEFS_SEQMUTEX_H
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#include <linux/mutex.h>
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struct seqmutex {
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struct mutex lock;
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u32 seq;
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};
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#define seqmutex_init(_lock) mutex_init(&(_lock)->lock)
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static inline bool seqmutex_trylock(struct seqmutex *lock)
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{
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return mutex_trylock(&lock->lock);
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}
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static inline void seqmutex_lock(struct seqmutex *lock)
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{
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mutex_lock(&lock->lock);
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lock->seq++;
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}
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static inline u32 seqmutex_unlock(struct seqmutex *lock)
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{
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u32 seq = lock->seq;
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mutex_unlock(&lock->lock);
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return seq;
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}
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static inline bool seqmutex_relock(struct seqmutex *lock, u32 seq)
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{
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if (lock->seq != seq || !mutex_trylock(&lock->lock))
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return false;
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if (lock->seq != seq) {
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mutex_unlock(&lock->lock);
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return false;
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}
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return true;
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}
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#endif /* _BCACHEFS_SEQMUTEX_H */
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