| Message ID | 20210908131021.774533-2-eesposit@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block layer: split block APIs in graph and I/O | expand |
On Wed, Sep 08, 2021 at 09:10:18AM -0400, Emanuele Giuseppe Esposito wrote: > When invoked from the main loop, this function is the same > as qemu_mutex_iothread_locked, and returns true if the BQL is held. > When invoked from iothreads or tests, it returns true only > if the current AioContext is the Main Loop. > > This essentially just extends qemu_mutex_iothread_locked to work > also in unit tests or other users like storage-daemon, that run > in the Main Loop but end up using the implementation in > stubs/iothread-lock.c. > > Using qemu_mutex_iothread_locked in unit tests defaults to false > because they use the implementation in stubs/iothread-lock, > making all assertions added in next patches fail despite the > AioContext is still the main loop. > > Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> > --- > include/qemu/main-loop.h | 13 +++++++++++++ > softmmu/cpus.c | 5 +++++ > stubs/iothread-lock.c | 5 +++++ > 3 files changed, 23 insertions(+) > > diff --git a/include/qemu/main-loop.h b/include/qemu/main-loop.h > index 8dbc6fcb89..c6547207f7 100644 > --- a/include/qemu/main-loop.h > +++ b/include/qemu/main-loop.h > @@ -245,6 +245,19 @@ AioContext *iohandler_get_aio_context(void); > */ > bool qemu_mutex_iothread_locked(void); > > +/** > + * qemu_in_main_thread: Return true if the function runs with BQL > + * or in the main loop AioContext. > + * > + * This function falls back to qemu_mutex_iothread_locked() if > + * called from the main loop, otherwise it checks if the current > + * AioContext is the main loop. This is useful to check that the BQL > + * is held, and not make it return false when invoked by unit > + * tests or other users like storage-daemon that end up using > + * stubs/iothread-lock.c implementation. > + */ > +bool qemu_in_main_thread(void); This description doesn't match the behavior because the "or in the main loop AioContext" part only applies to non softmmu builds (e.g. tests). Please phrase it so it's clear that this function is the same as qemu_mutex_iothread_locked() when softmmu/cpus.c is linked into the program. Otherwise it checks that the current AioContext is the global AioContext.
diff --git a/include/qemu/main-loop.h b/include/qemu/main-loop.h index 8dbc6fcb89..c6547207f7 100644 --- a/include/qemu/main-loop.h +++ b/include/qemu/main-loop.h @@ -245,6 +245,19 @@ AioContext *iohandler_get_aio_context(void); */ bool qemu_mutex_iothread_locked(void); +/** + * qemu_in_main_thread: Return true if the function runs with BQL + * or in the main loop AioContext. + * + * This function falls back to qemu_mutex_iothread_locked() if + * called from the main loop, otherwise it checks if the current + * AioContext is the main loop. This is useful to check that the BQL + * is held, and not make it return false when invoked by unit + * tests or other users like storage-daemon that end up using + * stubs/iothread-lock.c implementation. + */ +bool qemu_in_main_thread(void); + /** * qemu_mutex_lock_iothread: Lock the main loop mutex. * diff --git a/softmmu/cpus.c b/softmmu/cpus.c index 071085f840..3f61a3c31d 100644 --- a/softmmu/cpus.c +++ b/softmmu/cpus.c @@ -481,6 +481,11 @@ bool qemu_mutex_iothread_locked(void) return iothread_locked; } +bool qemu_in_main_thread(void) +{ + return qemu_mutex_iothread_locked(); +} + /* * The BQL is taken from so many places that it is worth profiling the * callers directly, instead of funneling them all through a single function. diff --git a/stubs/iothread-lock.c b/stubs/iothread-lock.c index 5b45b7fc8b..ff7386e42c 100644 --- a/stubs/iothread-lock.c +++ b/stubs/iothread-lock.c @@ -6,6 +6,11 @@ bool qemu_mutex_iothread_locked(void) return false; } +bool qemu_in_main_thread(void) +{ + return qemu_get_current_aio_context() == qemu_get_aio_context(); +} + void qemu_mutex_lock_iothread_impl(const char *file, int line) { }
When invoked from the main loop, this function is the same as qemu_mutex_iothread_locked, and returns true if the BQL is held. When invoked from iothreads or tests, it returns true only if the current AioContext is the Main Loop. This essentially just extends qemu_mutex_iothread_locked to work also in unit tests or other users like storage-daemon, that run in the Main Loop but end up using the implementation in stubs/iothread-lock.c. Using qemu_mutex_iothread_locked in unit tests defaults to false because they use the implementation in stubs/iothread-lock, making all assertions added in next patches fail despite the AioContext is still the main loop. Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> --- include/qemu/main-loop.h | 13 +++++++++++++ softmmu/cpus.c | 5 +++++ stubs/iothread-lock.c | 5 +++++ 3 files changed, 23 insertions(+)