[PATCH] drm/shmem: Cleanup drm_gem_shmem_create_with_handle()

[PATCH] drm/shmem: Cleanup drm_gem_shmem_create_with_handle()

[Rob Clark]

From: Rob Clark <robdclark@chromium.org>

Once we create the handle, the handle owns the reference.  Currently
nothing was doing anything with the shmem ptr after the handle was
created, but let's change drm_gem_shmem_create_with_handle() to not
return the pointer, so-as to not encourage problematic use of this
function in the future.  As a bonus, it makes the code a bit cleaner.

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/drm_gem_shmem_helper.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index f21f47737817..19406f4907df 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -415,7 +415,7 @@ void drm_gem_shmem_vunmap(struct drm_gem_shmem_object *shmem,
 }
 EXPORT_SYMBOL(drm_gem_shmem_vunmap);
 
-static struct drm_gem_shmem_object *
+static int
 drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
 				 struct drm_device *dev, size_t size,
 				 uint32_t *handle)
@@ -434,10 +434,8 @@ drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
 	ret = drm_gem_handle_create(file_priv, &shmem->base, handle);
 	/* drop reference from allocate - handle holds it now. */
 	drm_gem_object_put(&shmem->base);
-	if (ret)
-		return ERR_PTR(ret);
 
-	return shmem;
+	return ret;
 }
 
 /* Update madvise status, returns true if not purged, else
@@ -533,9 +531,7 @@ int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
 			args->size = PAGE_ALIGN(args->pitch * args->height);
 	}
 
-	shmem = drm_gem_shmem_create_with_handle(file, dev, args->size, &args->handle);
-
-	return PTR_ERR_OR_ZERO(shmem);
+	return drm_gem_shmem_create_with_handle(file, dev, args->size, &args->handle);
 }
 EXPORT_SYMBOL_GPL(drm_gem_shmem_dumb_create);
 
-- 
2.38.1

Re: [PATCH] drm/shmem: Cleanup drm_gem_shmem_create_with_handle()

[kernel test robot]

Hi Rob,

I love your patch! Perhaps something to improve:

[auto build test WARNING on drm-misc/drm-misc-next]
[also build test WARNING on drm/drm-next drm-exynos/exynos-drm-next drm-intel/for-linux-next drm-intel/for-linux-next-fixes drm-tip/drm-tip linus/master v6.2-rc4 next-20230119]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Rob-Clark/drm-shmem-Cleanup-drm_gem_shmem_create_with_handle/20230120-021440
base:   git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
patch link:    https://lore.kernel.org/r/20230119181325.2834875-1-robdclark%40gmail.com
patch subject: [PATCH] drm/shmem: Cleanup drm_gem_shmem_create_with_handle()
config: ia64-allyesconfig (https://download.01.org/0day-ci/archive/20230120/202301200511.h6Af907u-lkp@intel.com/config)
compiler: ia64-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/0de4f64a7edc0dcbf8ac711d79e203698fcd95a7
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Rob-Clark/drm-shmem-Cleanup-drm_gem_shmem_create_with_handle/20230120-021440
        git checkout 0de4f64a7edc0dcbf8ac711d79e203698fcd95a7
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=ia64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=ia64 SHELL=/bin/bash drivers/gpu/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   drivers/gpu/drm/drm_gem_shmem_helper.c: In function 'drm_gem_shmem_create_with_handle':
>> drivers/gpu/drm/drm_gem_shmem_helper.c:428:24: warning: returning 'struct drm_gem_shmem_object *' from a function with return type 'int' makes integer from pointer without a cast [-Wint-conversion]
     428 |                 return shmem;
         |                        ^~~~~
   drivers/gpu/drm/drm_gem_shmem_helper.c: In function 'drm_gem_shmem_dumb_create':
   drivers/gpu/drm/drm_gem_shmem_helper.c:521:38: warning: unused variable 'shmem' [-Wunused-variable]
     521 |         struct drm_gem_shmem_object *shmem;
         |                                      ^~~~~


vim +428 drivers/gpu/drm/drm_gem_shmem_helper.c

2194a63a818db7 Noralf Trønnes 2019-03-12  417  
0de4f64a7edc0d Rob Clark      2023-01-19  418  static int
2194a63a818db7 Noralf Trønnes 2019-03-12  419  drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
2194a63a818db7 Noralf Trønnes 2019-03-12  420  				 struct drm_device *dev, size_t size,
2194a63a818db7 Noralf Trønnes 2019-03-12  421  				 uint32_t *handle)
2194a63a818db7 Noralf Trønnes 2019-03-12  422  {
2194a63a818db7 Noralf Trønnes 2019-03-12  423  	struct drm_gem_shmem_object *shmem;
2194a63a818db7 Noralf Trønnes 2019-03-12  424  	int ret;
2194a63a818db7 Noralf Trønnes 2019-03-12  425  
cfe28f909ddd6c Daniel Vetter  2020-06-16  426  	shmem = drm_gem_shmem_create(dev, size);
2194a63a818db7 Noralf Trønnes 2019-03-12  427  	if (IS_ERR(shmem))
2194a63a818db7 Noralf Trønnes 2019-03-12 @428  		return shmem;
2194a63a818db7 Noralf Trønnes 2019-03-12  429  
2194a63a818db7 Noralf Trønnes 2019-03-12  430  	/*
2194a63a818db7 Noralf Trønnes 2019-03-12  431  	 * Allocate an id of idr table where the obj is registered
2194a63a818db7 Noralf Trønnes 2019-03-12  432  	 * and handle has the id what user can see.
2194a63a818db7 Noralf Trønnes 2019-03-12  433  	 */
2194a63a818db7 Noralf Trønnes 2019-03-12  434  	ret = drm_gem_handle_create(file_priv, &shmem->base, handle);
2194a63a818db7 Noralf Trønnes 2019-03-12  435  	/* drop reference from allocate - handle holds it now. */
be6ee102341bc4 Emil Velikov   2020-05-15  436  	drm_gem_object_put(&shmem->base);
2194a63a818db7 Noralf Trønnes 2019-03-12  437  
0de4f64a7edc0d Rob Clark      2023-01-19  438  	return ret;
2194a63a818db7 Noralf Trønnes 2019-03-12  439  }
2194a63a818db7 Noralf Trønnes 2019-03-12  440  

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