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

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