dropped qemu-devel by mistake. Paolo
Il lun 12 dic 2022, 23:16 Paolo Bonzini <pbonz...@redhat.com> ha scritto: > On 12/8/22 15:23, Markus Armbruster wrote: > > qemu/coroutine.h and qemu/lockable.h include each other. Neither > > header actually needs the other one. > > qemu/lockable.h wants qemu/coroutine.h because of the reference to > qemu_co_mutex_lock/unlock in the QEMU_MAKE_LOCKABLE macro. Said > reference only happens when the macro is used, so strictly speaking > only code that uses of qemu/lockable.h's functionality needs to > include qemu/coroutine.h. The order doesn't matter. > > qemu/coroutine.h similarly wants qemu/lockable.h only for a macro: it > uses QemuLockable for the prototype of qemu_co_queue_wait_impl, but > QemuLockable is defined in qemu/typedefs.h. On the other hand, the > qemu_co_queue_wait macro needs QEMU_MAKE_LOCKABLE. Again, the order > does not matter but callers of qemu_co_queue_wait appreciate it if > both files are included. > > So, this is why the inclusion loop works. This patch makes some > files include qemu/coroutine.h even if they only need qemu/lockable.h > for QEMU_LOCK_GUARD of a "regular" QemuMutex; for example, linux-user/ > does not use coroutines, so I'd like to avoid that it includes > qemu/coroutine.h. > > One way is to just keep the cycle. Another is to break the cycle is > as follows: > > 1) qemu/coroutine.h keeps including qemu/lockable.h > > 2) qemu/lockable.h is modified as follows to omit the reference to CoMutex: > > diff --git a/include/qemu/lockable.h b/include/qemu/lockable.h > index 86db7cb04c9c..db59656538a4 100644 > --- a/include/qemu/lockable.h > +++ b/include/qemu/lockable.h > @@ -71,9 +71,11 @@ qemu_null_lockable(void *x) > void *: qemu_null_lockable(x), \ > QemuMutex *: qemu_make_lockable(x, QML_OBJ_(x, mutex)), \ > QemuRecMutex *: qemu_make_lockable(x, QML_OBJ_(x, > rec_mutex)), \ > - CoMutex *: qemu_make_lockable(x, QML_OBJ_(x, co_mutex)), \ > + QEMU_MAKE_CO_MUTEX_LOCKABLE(x) \ > QemuSpin *: qemu_make_lockable(x, QML_OBJ_(x, spin))) > > +#define QEMU_MAKE_CO_MUTEX_LOCKABLE(x) > + > /** > * QEMU_MAKE_LOCKABLE_NONNULL - Make a polymorphic QemuLockable > * > > 3) the following hack is added in qemu/coroutine.h, right after including > qemu/lockable.h: > > #undef QEMU_MAKE_CO_MUTEX_LOCKABLE(x) > #define QEMU_MAKE_CO_MUTEX_LOCKABLE(x) \ > CoMutex *: qemu_make_lockable(x, QML_OBJ_(x, co_mutex)), > > > Neither is particularly pretty, so I vote for leaving things as is with > a comment above the two #include directives. > > Paolo >
