Thomas Zimmermann
2021-Nov-30 09:52 UTC
[PATCH] drm: Return error codes from struct drm_driver.gem_create_object
GEM helper libraries use struct drm_driver.gem_create_object to let
drivers override GEM object allocation. On failure, the call returns
NULL.
Change the semantics to make the calls return a pointer-encoded error.
This aligns the callback with its callers. Fixes the ingenic driver,
which already returns an error pointer.
Also update the callers to handle the involved types more strictly.
Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
There is an alternative patch at [1] that updates the value returned
by ingenics' gem_create_object to NULL. Fixing the interface to return
an errno code is more consistent with the rest of the GEM functions.
[1] https://lore.kernel.org/dri-devel/20211118111522.GD1147 at kili/
---
drivers/gpu/drm/drm_gem_cma_helper.c | 17 ++++++++++-------
drivers/gpu/drm/drm_gem_shmem_helper.c | 17 ++++++++++-------
drivers/gpu/drm/drm_gem_vram_helper.c | 4 ++--
drivers/gpu/drm/lima/lima_gem.c | 2 +-
drivers/gpu/drm/panfrost/panfrost_gem.c | 2 +-
drivers/gpu/drm/v3d/v3d_bo.c | 4 ++--
drivers/gpu/drm/vc4/vc4_bo.c | 2 +-
drivers/gpu/drm/vgem/vgem_drv.c | 2 +-
drivers/gpu/drm/virtio/virtgpu_object.c | 2 +-
include/drm/drm_drv.h | 5 +++--
10 files changed, 32 insertions(+), 25 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c
b/drivers/gpu/drm/drm_gem_cma_helper.c
index 7d4895de9e0d..cefd0cbf9deb 100644
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -67,18 +67,21 @@ __drm_gem_cma_create(struct drm_device *drm, size_t size,
bool private)
struct drm_gem_object *gem_obj;
int ret = 0;
- if (drm->driver->gem_create_object)
+ if (drm->driver->gem_create_object) {
gem_obj = drm->driver->gem_create_object(drm, size);
- else
- gem_obj = kzalloc(sizeof(*cma_obj), GFP_KERNEL);
- if (!gem_obj)
- return ERR_PTR(-ENOMEM);
+ if (IS_ERR(gem_obj))
+ return ERR_CAST(gem_obj);
+ cma_obj = to_drm_gem_cma_obj(gem_obj);
+ } else {
+ cma_obj = kzalloc(sizeof(*cma_obj), GFP_KERNEL);
+ if (!cma_obj)
+ return ERR_PTR(-ENOMEM);
+ gem_obj = &cma_obj->base;
+ }
if (!gem_obj->funcs)
gem_obj->funcs = &drm_gem_cma_default_funcs;
- cma_obj = container_of(gem_obj, struct drm_gem_cma_object, base);
-
if (private) {
drm_gem_private_object_init(drm, gem_obj, size);
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c
b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 0eeda1012364..7915047cb041 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -56,14 +56,17 @@ __drm_gem_shmem_create(struct drm_device *dev, size_t size,
bool private)
size = PAGE_ALIGN(size);
- if (dev->driver->gem_create_object)
+ if (dev->driver->gem_create_object) {
obj = dev->driver->gem_create_object(dev, size);
- else
- obj = kzalloc(sizeof(*shmem), GFP_KERNEL);
- if (!obj)
- return ERR_PTR(-ENOMEM);
-
- shmem = to_drm_gem_shmem_obj(obj);
+ if (IS_ERR(obj))
+ return ERR_CAST(obj);
+ shmem = to_drm_gem_shmem_obj(obj);
+ } else {
+ shmem = kzalloc(sizeof(*shmem), GFP_KERNEL);
+ if (!shmem)
+ return ERR_PTR(-ENOMEM);
+ obj = &shmem->base;
+ }
if (!obj->funcs)
obj->funcs = &drm_gem_shmem_funcs;
diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c
b/drivers/gpu/drm/drm_gem_vram_helper.c
index bfa386b98134..3f00192215d1 100644
--- a/drivers/gpu/drm/drm_gem_vram_helper.c
+++ b/drivers/gpu/drm/drm_gem_vram_helper.c
@@ -197,8 +197,8 @@ struct drm_gem_vram_object *drm_gem_vram_create(struct
drm_device *dev,
if (dev->driver->gem_create_object) {
gem = dev->driver->gem_create_object(dev, size);
- if (!gem)
- return ERR_PTR(-ENOMEM);
+ if (IS_ERR(gem))
+ return ERR_CAST(gem);
gbo = drm_gem_vram_of_gem(gem);
} else {
gbo = kzalloc(sizeof(*gbo), GFP_KERNEL);
diff --git a/drivers/gpu/drm/lima/lima_gem.c b/drivers/gpu/drm/lima/lima_gem.c
index 2723d333c608..f9a9198ef198 100644
--- a/drivers/gpu/drm/lima/lima_gem.c
+++ b/drivers/gpu/drm/lima/lima_gem.c
@@ -221,7 +221,7 @@ struct drm_gem_object *lima_gem_create_object(struct
drm_device *dev, size_t siz
bo = kzalloc(sizeof(*bo), GFP_KERNEL);
if (!bo)
- return NULL;
+ return ERR_PTR(-ENOMEM);
mutex_init(&bo->lock);
INIT_LIST_HEAD(&bo->va);
diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c
b/drivers/gpu/drm/panfrost/panfrost_gem.c
index 6d9bdb9180cb..ead65f5fa2bc 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gem.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
@@ -223,7 +223,7 @@ struct drm_gem_object *panfrost_gem_create_object(struct
drm_device *dev, size_t
obj = kzalloc(sizeof(*obj), GFP_KERNEL);
if (!obj)
- return NULL;
+ return ERR_PTR(-ENOMEM);
INIT_LIST_HEAD(&obj->mappings.list);
mutex_init(&obj->mappings.lock);
diff --git a/drivers/gpu/drm/v3d/v3d_bo.c b/drivers/gpu/drm/v3d/v3d_bo.c
index 0d9af62f69ad..6e3113f419f4 100644
--- a/drivers/gpu/drm/v3d/v3d_bo.c
+++ b/drivers/gpu/drm/v3d/v3d_bo.c
@@ -70,11 +70,11 @@ struct drm_gem_object *v3d_create_object(struct drm_device
*dev, size_t size)
struct drm_gem_object *obj;
if (size == 0)
- return NULL;
+ return ERR_PTR(-EINVAL);
bo = kzalloc(sizeof(*bo), GFP_KERNEL);
if (!bo)
- return NULL;
+ return ERR_PTR(-ENOMEM);
obj = &bo->base.base;
obj->funcs = &v3d_gem_funcs;
diff --git a/drivers/gpu/drm/vc4/vc4_bo.c b/drivers/gpu/drm/vc4/vc4_bo.c
index 8520e440dbd1..6d1281a343e9 100644
--- a/drivers/gpu/drm/vc4/vc4_bo.c
+++ b/drivers/gpu/drm/vc4/vc4_bo.c
@@ -391,7 +391,7 @@ struct drm_gem_object *vc4_create_object(struct drm_device
*dev, size_t size)
bo = kzalloc(sizeof(*bo), GFP_KERNEL);
if (!bo)
- return NULL;
+ return ERR_PTR(-ENOMEM);
bo->madv = VC4_MADV_WILLNEED;
refcount_set(&bo->usecnt, 0);
diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index a87eafa89e9f..c5e3e5457737 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -97,7 +97,7 @@ static struct drm_gem_object *vgem_gem_create_object(struct
drm_device *dev, siz
obj = kzalloc(sizeof(*obj), GFP_KERNEL);
if (!obj)
- return NULL;
+ return ERR_PTR(-ENOMEM);
/*
* vgem doesn't have any begin/end cpu access ioctls, therefore must use
diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c
b/drivers/gpu/drm/virtio/virtgpu_object.c
index 187e10da2f17..baef2c5f2aaf 100644
--- a/drivers/gpu/drm/virtio/virtgpu_object.c
+++ b/drivers/gpu/drm/virtio/virtgpu_object.c
@@ -139,7 +139,7 @@ struct drm_gem_object *virtio_gpu_create_object(struct
drm_device *dev,
shmem = kzalloc(sizeof(*shmem), GFP_KERNEL);
if (!shmem)
- return NULL;
+ return ERR_PTR(-ENOMEM);
dshmem = &shmem->base.base;
dshmem->base.funcs = &virtio_gpu_shmem_funcs;
diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index da0c836fe8e1..f6159acb8856 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -291,8 +291,9 @@ struct drm_driver {
/**
* @gem_create_object: constructor for gem objects
*
- * Hook for allocating the GEM object struct, for use by the CMA and
- * SHMEM GEM helpers.
+ * Hook for allocating the GEM object struct, for use by the CMA
+ * and SHMEM GEM helpers. Returns a GEM object on success, or an
+ * ERR_PTR()-encoded error code otherwise.
*/
struct drm_gem_object *(*gem_create_object)(struct drm_device *dev,
size_t size);
--
2.34.0
Dan Carpenter
2021-Dec-06 10:42 UTC
[PATCH] drm: Return error codes from struct drm_driver.gem_create_object
On Tue, Nov 30, 2021 at 10:52:55AM +0100, Thomas Zimmermann wrote:> GEM helper libraries use struct drm_driver.gem_create_object to let > drivers override GEM object allocation. On failure, the call returns > NULL. > > Change the semantics to make the calls return a pointer-encoded error. > This aligns the callback with its callers. Fixes the ingenic driver, > which already returns an error pointer. > > Also update the callers to handle the involved types more strictly. > > Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de> > --- > There is an alternative patch at [1] that updates the value returned > by ingenics' gem_create_object to NULL. Fixing the interface to return > an errno code is more consistent with the rest of the GEM functions. > > [1] https://lore.kernel.org/dri-devel/20211118111522.GD1147 at kili/My fix was already applied and backported to -stable etc... Your patch is not developed against a current tree so you broke it. That's the tricky thing with changing the API because say people wrote their code last week where returning NULL was correct. When they submit their driver upstream, everything will merge and build but it will break at runtime. For now, it's only vc4_create_object() which is broken. regards, dan carpenter