On 11.01.2017 12:56, Christian König wrote:
Am 11.01.2017 um 08:31 schrieb Nicolai Hähnle:
From: Nicolai Hähnle <nicolai.haeh...@amd.com>
ttm_bo_init checks that the reservation object is locked. This is
the caller's responsibility when resv != NULL. Otherwise, the inline
reservation object of the newly allocated buffer is used and must
explicitly be locked. Using a trylock is fine, since nobody else
has a reference to the reservation lock.
Good, catch. But while using trylock is fine, why do you need to use it
in the first place?
Or is this a question about trylock vs. lock?
Actually, now that I think about this again, perhaps the following
sequence would be possible:
1. Create the main bo in amdgpu_bo_create.
2. Other thread, for whatever reason, tries to make space and evict the
bo, and probably locks the reservation for that?
3. amdgpu_bo_create continues, calls the trylock which now fails.
Nicolai
Regards,
Christian.
Signed-off-by: Nicolai Hähnle <nicolai.haeh...@amd.com>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index 11c12c4d..357eed9 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -465,21 +465,32 @@ int amdgpu_bo_create(struct amdgpu_device *adev,
amdgpu_ttm_placement_init(adev, &placement,
placements, domain, flags);
r = amdgpu_bo_create_restricted(adev, size, byte_align, kernel,
domain, flags, sg, &placement,
resv, bo_ptr);
if (r)
return r;
if (amdgpu_need_backup(adev) && (flags &
AMDGPU_GEM_CREATE_SHADOW)) {
+ if (!resv) {
+ bool locked;
+
+ locked = ww_mutex_trylock(&(*bo_ptr)->tbo.resv->lock);
+ WARN_ON(!locked);
+ }
+
r = amdgpu_bo_create_shadow(adev, size, byte_align, (*bo_ptr));
+
+ if (!resv)
+ ww_mutex_unlock(&(*bo_ptr)->tbo.resv->lock);
+
if (r)
amdgpu_bo_unref(bo_ptr);
}
return r;
}
int amdgpu_bo_backup_to_shadow(struct amdgpu_device *adev,
struct amdgpu_ring *ring,
struct amdgpu_bo *bo,
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