Hierarchical Lock Relationships

NOTE(RWLOCK_COVERS_LOCKS(RwlockName, LockNameList))

This annotation is allowed both outside and inside a function definition. It tells LockLint that a hierarchical relationship exists between a readers-writer lock and a set of other locks. Under these rules, holding the cover lock for write access affords a thread access to all data protected by the covered locks. Also, a thread must hold the cover lock for read access whenever holding any of the covered locks.

Using a readers-writer lock to cover another lock in this way is simply a convention; there is no special lock type. However, if LockLint is not told about this coverage relationship, it assumes that the locks are being used according to the usual conventions and generates error messages.

The following example specifies that member lock of unnamed foo structures covers member lock of unnamed bar and zot structures:

NOTE(RWLOCK_COVERS_LOCKS(foo::lock, {bar zot}::lock))