[PATCH] dma-buf: Provide wrappers for reservation's lock

[Daniel Vetter]

On Sun, Dec 11, 2016 at 04:05:21PM -0500, Alex Deucher wrote:
> On Sun, Dec 11, 2016 at 12:12 PM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > On Tue, Nov 15, 2016 at 10:43:34PM +0100, Daniel Vetter wrote:
> >> On Tue, Nov 15, 2016 at 03:46:42PM +0000, Chris Wilson wrote:
> >> > Joonas complained that writing ww_mutex_lock(&resv->lock, ctx) was too
> >> > intrusive compared to reservation_object_lock(resv, ctx);
> >> >
> >> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> >> > Cc: Sumit Semwal <sumit.semwal at linaro.org>
> >> > Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> >> > ---
> >> >  include/linux/reservation.h | 34 ++++++++++++++++++++++++++++++++++
> >> >  1 file changed, 34 insertions(+)
> >> >
> >> > diff --git a/include/linux/reservation.h b/include/linux/reservation.h
> >> > index ed238961e1bf..9cfc0d857862 100644
> >> > --- a/include/linux/reservation.h
> >> > +++ b/include/linux/reservation.h
> >> > @@ -129,6 +129,40 @@ reservation_object_fini(struct reservation_object *obj)
> >> >  }
> >> >
> >> >  /**
> >> > + * reservation_object_lock - lock the reservation object
> >> > + * @obj: the reservation object
> >> > + * @ctx: the locking context
> >> > + *
> >> > + * Locks the reservation object for exclusive access and modification. Note,
> >> > + * that the lock is only against other writers, readers will run concurrently
> >> > + * with a writer under RCU. The seqlock is used to notify readers if they
> >> > + * overlap with a writer.
> >> > + *
> >> > + * As the reservation object may be locked by multiple parties in an
> >> > + * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
> >>
> >> s/#/&/ for struct references. Otherwise the magic hotlink won't appear
> >> (once we get around to pulling all the core docs into the overall sphinx
> >> build). I can fix this while applying if everyone else is ok with the
> >> patch - imo it makes sense.
> >
> > Anyone want to second these ww_mutex wrappers for reservation objects?
> 
> Looks good to me.
> 
> Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

Applied to drm-misc, thanks.
-Daniel

> 
> >
> >> > + * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
> >> > + * object may be locked by itself by passing NULL as @ctx.
> >> > + */
> >> > +static inline int
> >> > +reservation_object_lock(struct reservation_object *obj,
> >> > +                   struct ww_acquire_ctx *ctx)
> >> > +{
> >> > +   return ww_mutex_lock(&obj->lock, ctx);
> >> > +}
> >> > +
> >> > +/**
> >> > + * reservation_object_unlock - unlock the reservation object
> >> > + * @obj: the reservation object
> >> > + *
> >> > + * Unlocks the reservation object following exclusive access.
> >> > + */
> >> > +static inline void
> >> > +reservation_object_unlock(struct reservation_object *obj)
> >> > +{
> >> > +   ww_mutex_unlock(&obj->lock);
> >> > +}
> >> > +
> >> > +/**
> >> >   * reservation_object_get_excl - get the reservation object's
> >> >   * exclusive fence, with update-side lock held
> >> >   * @obj: the reservation object
> >
> > --
> > Chris Wilson, Intel Open Source Technology Centre
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch