linux-kernel - RE: [PATCH] drm/ttm: optimize errors checking and free

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Date:   Tue, 2 Jan 2018 03:05:42 +0000
From:   "He, Roger" <Hongbo.He@....com>
To:     Xiongwei Song <sxwjean@...il.com>,
        "Koenig, Christian" <Christian.Koenig@....com>,
        "airlied@...ux.ie" <airlied@...ux.ie>
CC:     "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] drm/ttm: optimize errors checking and free _manager when
 finishing



-----Original Message-----
From: Xiongwei Song [mailto:sxwjean@...il.com] 
Sent: Sunday, December 31, 2017 7:40 PM
To: Koenig, Christian <Christian.Koenig@....com>; He, Roger <Hongbo.He@....com>; airlied@...ux.ie
Cc: dri-devel@...ts.freedesktop.org; linux-kernel@...r.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@...il.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.


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