Re: [PATCH] drm/ttm: optimize errors checking and free _manager when finishing

Am 02.01.2018 um 04:05 schrieb He, Roger:

-----Original Message----- From: Xiongwei Song [mailto:sxwjean@gmail.com] Sent: Sunday, December 31, 2017 7:40 PM To: Koenig, Christian Christian.Koenig@amd.com; He, Roger Hongbo.He@amd.com; airlied@linux.ie Cc: dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org Subject: [PATCH] drm/ttm: optimize errors checking and free _manager when finishing

In the function ttm_page_alloc_init, kzalloc call is made for variable _manager, we need to check its return value, it may return NULL.

In the function ttm_page_alloc_fini, we need to call kfree for variable _manager, instead of make _manager NULL directly.

Signed-off-by: Xiongwei Song sxwjean@gmail.com

drivers/gpu/drm/ttm/ttm_page_alloc.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c index b5ba6441489f..e20a0b8e352b 100644 --- a/drivers/gpu/drm/ttm/ttm_page_alloc.c +++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c @@ -1007,6 +1007,10 @@ int ttm_page_alloc_init(struct ttm_mem_global *glob, unsigned max_pages) pr_info("Initializing pool allocator\n");

_manager = kzalloc(sizeof(*_manager), GFP_KERNEL);

• if (!_manager) {

• ret = -ENOMEM;
  

• goto out;
  

• }

Seems we only need above here for this patch I think. The rest is no need, because ttm_pool_kobj_release will kfree _manager.

Yes, agree. Freeing it again in ttm_page_alloc_fini will actually double free the memory and probably cause some problems.

Please refine the patch with only the additional error handling.

Regards, Christian.

Thanks Roger(Hongbo.He)

ttm_page_pool_init_locked(&_manager->wc_pool, GFP_HIGHUSER, "wc", 0);

@@ -1034,13 +1038,17 @@ int ttm_page_alloc_init(struct ttm_mem_global *glob, unsigned max_pages) &glob->kobj, "pool"); if (unlikely(ret != 0)) { kobject_put(&_manager->kobj);

• _manager = NULL;
  

• return ret;
  

• goto out_free_mgr;
  

  }

  ttm_pool_mm_shrink_init(_manager);

  return 0;

+out_free_mgr:

• kfree(_manager);
• _manager = NULL;

+out:

• return ret; }

  void ttm_page_alloc_fini(void)

@@ -1055,6 +1063,7 @@ void ttm_page_alloc_fini(void) ttm_page_pool_free(&_manager->pools[i], FREE_ALL_PAGES, true);

kobject_put(&_manager->kobj);

• kfree(_manager); _manager = NULL; }

-- 2.15.1