Am 18.09.2018 um 10:16 schrieb Zhu, Rex:
-----Original Message-----
From: Christian König <ckoenig.leichtzumer...@gmail.com>
Sent: Tuesday, September 18, 2018 3:14 PM
To: Zhu, Rex <rex....@amd.com>; amd-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/amdgpu: don't try to unreserve NULL pointer
Am 18.09.2018 um 08:16 schrieb Zhu, Rex:
-----Original Message-----
From: amd-gfx <amd-gfx-boun...@lists.freedesktop.org> On Behalf Of
Christian König
Sent: Tuesday, September 18, 2018 2:07 AM
To: amd-gfx@lists.freedesktop.org
Subject: [PATCH] drm/amdgpu: don't try to unreserve NULL pointer
Don't try to unreserve a BO we doesn't allocated.
Fixes: 07012fdd497e drm/amdgpu: don't allocate zero sized kernel BOs
Signed-off-by: Christian König <christian.koe...@amd.com>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index 84d82d5382f9..c1387efc0c91 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -348,7 +348,8 @@ int amdgpu_bo_create_kernel(struct
amdgpu_device
*adev,
if (r)
return r;
- amdgpu_bo_unreserve(*bo_ptr);
+ if (*bo_ptr)
+ amdgpu_bo_unreserve(*bo_ptr);
return 0;
}
It is weird.
If we return true for allocate bo with size 0.
Does that mean we need to check all the bo_ptr before we use them.
No, allocating a BO with zero size doesn't make much sense and was
essentially undefined behavior previously.
So now we get a defined behavior, but not necessary the one you expected.
Is that only a rhetorical question or really a problem somewhere?
Logically, the code is trick.
Yeah, that is not a bad argument.
But it also makes the function more useful, e.g. we don't need size
checks any more whenever an optional BO is allocated.
It also make the code
if (r)
return r;
redundant.
Actually that is not correct.
When an error happens the *bo_ptr is not modified at all. So we could
then try to unreserve a BO which was never reserved.
Christian.
Regards
Rex
Regards,
Christian.
Best Regards
Rex
--
2.14.1
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