On Mon, Nov 11, 2024 at 04:47:49PM +0530, Neeraj Upadhyay wrote:
>
> > +/**
> > + * srcu_read_unlock_lite - unregister a old reader from an SRCU-protected
> > structure.
> > + * @ssp: srcu_struct in which to unregister the old reader.
> > + * @idx: return value from corresponding srcu_read_lock().
> > + *
> > + * Exit a light-weight SRCU read-side critical section.
> > + */
> > +static inline void srcu_read_unlock_lite(struct srcu_struct *ssp, int idx)
> > + __releases(ssp)
> > +{
> > + WARN_ON_ONCE(idx & ~0x1);
> > + srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_LITE);
> > + srcu_lock_release(&ssp->dep_map);
> > + __srcu_read_unlock(ssp, idx);
>
> s/__srcu_read_unlock/__srcu_read_unlock_lite/ ?
Right you are! I am testing the patch.
The effect of this bug is that srcu_read_unlock_lite() has a needless
memory barrier and fails to check for RCU watching, so not a blazing
emergency. But it does mean that Andrii was only seeing half of the
performance benefit of using _lite().
Thanx, Paul
