On Fri, Apr 01, 2022 at 10:21:22AM +0200, Christian König wrote:
> Daniel any more comments on this one here?
>
> It's the prerequisite to a bunch of other patches and I would like to get it
> out of my feet.
Apologies for the miss, I thought I've r-b stamped this one already.
>
> Thanks,
> Christian.
>
> Am 21.03.22 um 14:58 schrieb Christian König:
> > Add a function to simplify getting a single fence for all the fences in
> > the dma_resv object.
> >
> > v2: fix ref leak in error handling
> >
> > Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> > ---
> > drivers/dma-buf/dma-resv.c | 52 ++++++++++++++++++++++++++++++++++++++
> > include/linux/dma-resv.h | 2 ++
> > 2 files changed, 54 insertions(+)
> >
> > diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> > index 5001e9b4420a..c09fd8da0c85 100644
> > --- a/drivers/dma-buf/dma-resv.c
> > +++ b/drivers/dma-buf/dma-resv.c
> > @@ -34,6 +34,7 @@
> > */
> > #include <linux/dma-resv.h>
> > +#include <linux/dma-fence-array.h>
> > #include <linux/export.h>
> > #include <linux/mm.h>
> > #include <linux/sched/mm.h>
> > @@ -650,6 +651,57 @@ int dma_resv_get_fences(struct dma_resv *obj, bool write,
> > }
> > EXPORT_SYMBOL_GPL(dma_resv_get_fences);
> > +/**
> > + * dma_resv_get_singleton - Get a single fence for all the fences
> > + * @obj: the reservation object
> > + * @write: true if we should return all fences
> > + * @fence: the resulting fence
> > + *
> > + * Get a single fence representing all the fences inside the resv object.
> > + * Returns either 0 for success or -ENOMEM.
> > + *
> > + * Warning: This can't be used like this when adding the fence back to the resv
> > + * object since that can lead to stack corruption when finalizing the
> > + * dma_fence_array.
Please add the standard boilerplate here:
Returns 0 on success and negative error values on failure.
> > + */
> > +int dma_resv_get_singleton(struct dma_resv *obj, bool write,
> > + struct dma_fence **fence)
> > +{
> > + struct dma_fence_array *array;
> > + struct dma_fence **fences;
> > + unsigned count;
> > + int r;
> > +
> > + r = dma_resv_get_fences(obj, write, &count, &fences);
Deep down in here we already have the dma_resv_assert_held, so I'm happy.
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> > + if (r)
> > + return r;
> > +
> > + if (count == 0) {
> > + *fence = NULL;
> > + return 0;
> > + }
> > +
> > + if (count == 1) {
> > + *fence = fences[0];
> > + kfree(fences);
> > + return 0;
> > + }
> > +
> > + array = dma_fence_array_create(count, fences,
> > + dma_fence_context_alloc(1),
> > + 1, false);
> > + if (!array) {
> > + while (count--)
> > + dma_fence_put(fences[count]);
> > + kfree(fences);
> > + return -ENOMEM;
> > + }
> > +
> > + *fence = &array->base;
> > + return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(dma_resv_get_singleton);
> > +
> > /**
> > * dma_resv_wait_timeout - Wait on reservation's objects
> > * shared and/or exclusive fences.
> > diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
> > index 202cc65d0621..08512c1e215d 100644
> > --- a/include/linux/dma-resv.h
> > +++ b/include/linux/dma-resv.h
> > @@ -449,6 +449,8 @@ void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context,
> > void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
> > int dma_resv_get_fences(struct dma_resv *obj, bool write,
> > unsigned int *num_fences, struct dma_fence ***fences);
> > +int dma_resv_get_singleton(struct dma_resv *obj, bool write,
> > + struct dma_fence **fence);
> > int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
> > long dma_resv_wait_timeout(struct dma_resv *obj, bool wait_all, bool intr,
> > unsigned long timeout);
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
