From: Luc Michel <[email protected]> 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 <[email protected]> Reviewed-by: Philippe Mathieu-Daudé <[email protected]> Message-Id: <[email protected]> Fixes: 988fcafc73 ("seqlock: add QemuLockable support", 2018-08-23) Signed-off-by: Paolo Bonzini <[email protected]> --- include/qemu/seqlock.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/qemu/seqlock.h b/include/qemu/seqlock.h index fd408b7ec5..8b6b4ee4bb 100644 --- a/include/qemu/seqlock.h +++ b/include/qemu/seqlock.h @@ -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)) -- 2.21.0
