[Outreachy kernel] Re: [PATCH] gpu: drm: Use list_first_entry instead of list_entry

[Julia Lawall]

On Mon, 19 Mar 2018, Christian König wrote:

> Mhm, actually that patch isn't correct. What we grab get here is the next
> entry, not the first one.
>
> We don't have an alias list_next_entry for list_first_entry?

As compared to the semantic patch I proposed earlier today, it would seem
that list_first_entry is useful when the types are different?  One would
have to check the result of course, but a list eleemnt with the same type
as the structure that contains the list might be unlikely?

julia

>
> Regards,
> Christian.
>
> Am 18.03.2018 um 22:51 schrieb Arushi Singhal:
> > This patch replaces list_entry with list_first_entry as it makes the
> > code more clear.
> > Done using coccinelle:
> >
> > @@
> > expression e;
> > @@
> > (
> > - list_entry(e->next,
> > + list_first_entry(e,
> >    ...)
> > |
> > - list_entry(e->prev,
> > + list_last_entry(e,
> >    ...)
> > )
> >
> > Signed-off-by: Arushi Singhal <arushisinghal19971997 at gmail.com>
> > ---
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_sa.c | 4 ++--
> >   drivers/gpu/drm/omapdrm/dss/display.c  | 4 ++--
> >   drivers/gpu/drm/radeon/radeon_sa.c     | 4 ++--
> >   3 files changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sa.c
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_sa.c
> > index 3144400..646f593 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sa.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sa.c
> > @@ -158,7 +158,7 @@ static void amdgpu_sa_bo_try_free(struct
> > amdgpu_sa_manager *sa_manager)
> >   	if (sa_manager->hole->next == &sa_manager->olist)
> >   		return;
> >   -	sa_bo = list_entry(sa_manager->hole->next, struct amdgpu_sa_bo,
> > olist);
> > +	sa_bo = list_first_entry(sa_manager->hole, struct amdgpu_sa_bo,
> > olist);
> >   	list_for_each_entry_safe_from(sa_bo, tmp, &sa_manager->olist, olist) {
> >   		if (sa_bo->fence == NULL ||
> >   		    !dma_fence_is_signaled(sa_bo->fence)) {
> > @@ -183,7 +183,7 @@ static inline unsigned amdgpu_sa_bo_hole_eoffset(struct
> > amdgpu_sa_manager *sa_ma
> >   	struct list_head *hole = sa_manager->hole;
> >     	if (hole->next != &sa_manager->olist) {
> > -		return list_entry(hole->next, struct amdgpu_sa_bo,
> > olist)->soffset;
> > +		return list_first_entry(hole, struct amdgpu_sa_bo,
> > olist)->soffset;
> >   	}
> >   	return sa_manager->size;
> >   }
> > diff --git a/drivers/gpu/drm/omapdrm/dss/display.c
> > b/drivers/gpu/drm/omapdrm/dss/display.c
> > index 0c9480b..fb9ecae 100644
> > --- a/drivers/gpu/drm/omapdrm/dss/display.c
> > +++ b/drivers/gpu/drm/omapdrm/dss/display.c
> > @@ -158,8 +158,8 @@ struct omap_dss_device *omap_dss_get_next_device(struct
> > omap_dss_device *from)
> >   				goto out;
> >   			}
> >   -			dssdev = list_entry(l->next, struct omap_dss_device,
> > -					panel_list);
> > +			dssdev = list_first_entry(l, struct omap_dss_device,
> > +						  panel_list);
> >   			omap_dss_get_device(dssdev);
> >   			goto out;
> >   		}
> > diff --git a/drivers/gpu/drm/radeon/radeon_sa.c
> > b/drivers/gpu/drm/radeon/radeon_sa.c
> > index 197b157..66c0482 100644
> > --- a/drivers/gpu/drm/radeon/radeon_sa.c
> > +++ b/drivers/gpu/drm/radeon/radeon_sa.c
> > @@ -158,7 +158,7 @@ static void radeon_sa_bo_try_free(struct
> > radeon_sa_manager *sa_manager)
> >   	if (sa_manager->hole->next == &sa_manager->olist)
> >   		return;
> >   -	sa_bo = list_entry(sa_manager->hole->next, struct radeon_sa_bo,
> > olist);
> > +	sa_bo = list_first_entry(sa_manager->hole, struct radeon_sa_bo,
> > olist);
> >   	list_for_each_entry_safe_from(sa_bo, tmp, &sa_manager->olist, olist) {
> >   		if (sa_bo->fence == NULL ||
> > !radeon_fence_signaled(sa_bo->fence)) {
> >   			return;
> > @@ -182,7 +182,7 @@ static inline unsigned radeon_sa_bo_hole_eoffset(struct
> > radeon_sa_manager *sa_ma
> >   	struct list_head *hole = sa_manager->hole;
> >     	if (hole->next != &sa_manager->olist) {
> > -		return list_entry(hole->next, struct radeon_sa_bo,
> > olist)->soffset;
> > +		return list_first_entry(hole, struct radeon_sa_bo,
> > olist)->soffset;
> >   	}
> >   	return sa_manager->size;
> >   }
>
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