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seqlock: fix seqlock_write_unlock_impl function 

The seqlock write unlock function was incorrectly calling
seqlock_write_begin() instead of seqlock_write_end(), and was releasing
the lock before incrementing the sequence. This could lead to a race
condition and a corrupted sequence number becoming odd even though the
lock is not held.

Signed-off-by: Luc Michel <luc.michel@greensocs.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200129144948.2161551-1-luc.michel@greensocs.com>
Fixes: 988fcafc73 ("seqlock: add QemuLockable support", 2018-08-23)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Luc Michel 2020-01-29 15:49:48 +01:00 committed by Paolo Bonzini
parent 4903602eae
commit e261b36810
1 changed files with 2 additions and 2 deletions
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4
include/qemu/seqlock.h
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@ -55,11 +55,11 @@ static inline void seqlock_write_lock_impl(QemuSeqLock *sl, QemuLockable *lock)
#define seqlock_write_lock(sl, lock) \
seqlock_write_lock_impl(sl, QEMU_MAKE_LOCKABLE(lock))
/* Lock out other writers and update the count. */
/* Update the count and release the lock. */
static inline void seqlock_write_unlock_impl(QemuSeqLock *sl, QemuLockable *lock)
{
seqlock_write_end(sl);
qemu_lockable_unlock(lock);
seqlock_write_begin(sl);
}
#define seqlock_write_unlock(sl, lock) \
seqlock_write_unlock_impl(sl, QEMU_MAKE_LOCKABLE(lock))