* Eric Blake (ebl...@redhat.com) wrote:
> On 9/11/19 11:42 AM, Dr. David Alan Gilbert (git) wrote:
> > From: "Dr. David Alan Gilbert" <dgilb...@redhat.com>
> >
> > RCU_READ_LOCK_AUTO takes the rcu_read_lock and then uses glib's
> > g_auto infrastrcture (and thus whatever the compilers hooks are) to
> > release it on all exits of the block.
> >
> > Note this macro has a variable declaration in, and hence is not in
> > a while loop.
> >
> > Signed-off-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
> > ---
> > include/qemu/rcu.h | 12 ++++++++++++
> > 1 file changed, 12 insertions(+)
> >
> > diff --git a/include/qemu/rcu.h b/include/qemu/rcu.h
> > index 22876d1428..6a25b27d28 100644
> > --- a/include/qemu/rcu.h
> > +++ b/include/qemu/rcu.h
> > @@ -154,6 +154,18 @@ extern void call_rcu1(struct rcu_head *head, RCUCBFunc
> > *func);
> > }), \
> > (RCUCBFunc *)g_free);
> >
> > +typedef char rcu_read_auto_t;
>
> Declaring new types ending in _t collides with the namespace reserved by
> POSIX. While I don't think it will bite us, it's still worth
> considering if a different name is better.
Thanks, I've renamed it to 'RCUReadAuto' which is closer to what we
normally use for typedef's (albeit normally of structs)
Dave
> > +static inline void rcu_read_auto_unlock(rcu_read_auto_t *r)
> > +{
> > + rcu_read_unlock();
> > +}
> > +
> > +G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(rcu_read_auto_t, rcu_read_auto_unlock)
> > +
> > +#define RCU_READ_LOCK_AUTO g_auto(rcu_read_auto_t) \
> > + _rcu_read_auto = 'x'; \
>
> I'm a bit lost at where _rcu_read_auto is declared. (I could understand
> if an earlier macro had created that typedef via concatenating _ with
> rcu_read_auto_t, but making the preprocessor drop _t is not possible. Is
> this a typo, and if so, why did the compiler not complain?)
>
> > + rcu_read_lock();
> > +
> > #ifdef __cplusplus
> > }
> > #endif
> >
>
> --
> Eric Blake, Principal Software Engineer
> Red Hat, Inc. +1-919-301-3226
> Virtualization: qemu.org | libvirt.org
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
