diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/qemu/coroutine.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/include/qemu/coroutine.h b/include/qemu/coroutine.h index a4509bd977..9aff9a735e 100644 --- a/include/qemu/coroutine.h +++ b/include/qemu/coroutine.h @@ -229,6 +229,24 @@ void qemu_co_rwlock_init(CoRwlock *lock); void qemu_co_rwlock_rdlock(CoRwlock *lock); /** + * Write Locks the CoRwlock from a reader. This is a bit more efficient than + * @qemu_co_rwlock_unlock followed by a separate @qemu_co_rwlock_wrlock. + * However, if the lock cannot be upgraded immediately, control is transferred + * to the caller of the current coroutine. Also, @qemu_co_rwlock_upgrade + * only overrides CoRwlock fairness if there are no concurrent readers, so + * another writer might run while @qemu_co_rwlock_upgrade blocks. + */ +void qemu_co_rwlock_upgrade(CoRwlock *lock); + +/** + * Downgrades a write-side critical section to a reader. Downgrading with + * @qemu_co_rwlock_downgrade never blocks, unlike @qemu_co_rwlock_unlock + * followed by @qemu_co_rwlock_rdlock. This makes it more efficient, but + * may also sometimes be necessary for correctness. + */ +void qemu_co_rwlock_downgrade(CoRwlock *lock); + +/** * Write Locks the mutex. If the lock cannot be taken immediately because * of a parallel reader, control is transferred to the caller of the current * coroutine. |