On 15.02.2017 04:16, zhoucm1 wrote:
On 2017年02月14日 18:37, Nicolai Hähnle wrote:
From: Nicolai Hähnle <nicolai.haehnle@xxxxxxx>
Allow callers to opt out of calling ttm_bo_validate immediately. This
allows more flexibility in how locking of the reservation object is
done, which is needed to fix a locking bug (destroy locked mutex)
in amdgpu.
Signed-off-by: Nicolai Hähnle <nicolai.haehnle@xxxxxxx>
---
drivers/gpu/drm/ttm/ttm_bo.c | 62
+++++++++++++++++++++++++++++---------------
include/drm/ttm/ttm_bo_api.h | 45 ++++++++++++++++++++++++++++++++
2 files changed, 86 insertions(+), 21 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 76bee42..ce4c0f5 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -1120,41 +1120,30 @@ int ttm_bo_validate(struct ttm_buffer_object *bo,
}
EXPORT_SYMBOL(ttm_bo_validate);
-int ttm_bo_init(struct ttm_bo_device *bdev,
- struct ttm_buffer_object *bo,
- unsigned long size,
- enum ttm_bo_type type,
- struct ttm_placement *placement,
- uint32_t page_alignment,
- bool interruptible,
- struct file *persistent_swap_storage,
- size_t acc_size,
- struct sg_table *sg,
- struct reservation_object *resv,
- void (*destroy) (struct ttm_buffer_object *))
+int ttm_bo_init_top(struct ttm_bo_device *bdev,
+ struct ttm_buffer_object *bo,
+ unsigned long size,
+ enum ttm_bo_type type,
+ uint32_t page_alignment,
+ struct file *persistent_swap_storage,
+ size_t acc_size,
+ struct sg_table *sg,
+ struct reservation_object *resv,
+ void (*destroy) (struct ttm_buffer_object *))
{
int ret = 0;
unsigned long num_pages;
struct ttm_mem_global *mem_glob = bdev->glob->mem_glob;
- bool locked;
ret = ttm_mem_global_alloc(mem_glob, acc_size, false, false);
if (ret) {
pr_err("Out of kernel memory\n");
- if (destroy)
- (*destroy)(bo);
- else
- kfree(bo);
return -ENOMEM;
}
num_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (num_pages == 0) {
pr_err("Illegal buffer object size\n");
- if (destroy)
- (*destroy)(bo);
- else
- kfree(bo);
ttm_mem_global_free(mem_glob, acc_size);
return -EINVAL;
}
@@ -1204,6 +1193,37 @@ int ttm_bo_init(struct ttm_bo_device *bdev,
ret = drm_vma_offset_add(&bdev->vma_manager, &bo->vma_node,
bo->mem.num_pages);
if (ret && !resv), we should call
reservation_object_fini(&bo->ttm_resv), right?
Good point, though actually, ret can never be != 0 here, so this can be
simplified a bit.
+ return ret;
+}
+EXPORT_SYMBOL(ttm_bo_init_top);
+
+int ttm_bo_init(struct ttm_bo_device *bdev,
+ struct ttm_buffer_object *bo,
+ unsigned long size,
+ enum ttm_bo_type type,
+ struct ttm_placement *placement,
+ uint32_t page_alignment,
+ bool interruptible,
+ struct file *persistent_swap_storage,
+ size_t acc_size,
+ struct sg_table *sg,
+ struct reservation_object *resv,
+ void (*destroy) (struct ttm_buffer_object *))
+{
+ bool locked;
+ int ret;
+
Can we lock resv anyway before ttm_bo_init_top like what you did in
patch #3? if yes, seems we don't need patch#3 any more, right?
if (!resv) {
bool locked;
reservation_object_init(&bo->tbo.ttm_resv);
locked = ww_mutex_trylock(&bo->tbo.ttm_resv.lock);
WARN_ON(!locked);
}
r = ttm_bo_init_top(&adev->mman.bdev, &bo->tbo, size, type,
page_align, NULL,
acc_size, sg, resv ? resv : &bo->tbo.ttm_resv,
&amdgpu_ttm_bo_destroy);
No, because there's still different behavior when it comes to unlocking.
There are three different behaviors that are needed:
1. resv == NULL, and leaving ttm_bo_init with the BO unreserved.
2. resv != NULL, and not changing the reserved status during initialization.
3. resv != NULL, and leaving initialization with the BO reserved, but
unlocking when the BO is destroyed.
1+2 can be expressed well with the ttm_bo_init interface, but 3 cannot.
I think a possible alternative would be to change ttm_bo_init so that it
always returns on success with the BO reserved, but that would require
changing all the drivers, and I don't really see the advantage over just
being more explicit in each driver.
Cheers,
Nicolai
Regards,
David Zhou
+ ret = ttm_bo_init_top(bdev, bo, size, type, page_alignment,
+ persistent_swap_storage, acc_size, sg, resv,
+ destroy);
+ if (ret) {
+ if (destroy)
+ (*destroy)(bo);
+ else
+ kfree(bo);
+ return ret;
+ }
+
/* passed reservation objects should already be locked,
* since otherwise lockdep will be angered in radeon.
*/
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index f195899..d44b8e4 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -453,6 +453,51 @@ size_t ttm_bo_dma_acc_size(struct ttm_bo_device
*bdev,
unsigned struct_size);
/**
+ * ttm_bo_init_top
+ *
+ * @bdev: Pointer to a ttm_bo_device struct.
+ * @bo: Pointer to a ttm_buffer_object to be initialized.
+ * @size: Requested size of buffer object.
+ * @type: Requested type of buffer object.
+ * @flags: Initial placement flags.
+ * @page_alignment: Data alignment in pages.
+ * @persistent_swap_storage: Usually the swap storage is deleted for
buffers
+ * pinned in physical memory. If this behaviour is not desired, this
member
+ * holds a pointer to a persistent shmem object. Typically, this would
+ * point to the shmem object backing a GEM object if TTM is used to
back a
+ * GEM user interface.
+ * @acc_size: Accounted size for this object.
+ * @resv: Pointer to a reservation_object, or NULL to let ttm
allocate one.
+ * @destroy: Destroy function. Use NULL for kfree().
+ *
+ * This function initializes a pre-allocated struct ttm_buffer_object.
+ * As this object may be part of a larger structure, this function,
+ * together with the @destroy function,
+ * enables driver-specific objects derived from a ttm_buffer_object.
+ *
+ * Unlike ttm_bo_init, @bo is not validated, and when an error is
returned,
+ * the caller is responsible for freeing @bo (but the setup performed by
+ * ttm_bo_init_top itself is cleaned up).
+ *
+ * On successful return, the object kref and list_kref are set to 1.
+ *
+ * Returns
+ * -ENOMEM: Out of memory.
+ * -EINVAL: Invalid buffer size.
+ */
+
+extern int ttm_bo_init_top(struct ttm_bo_device *bdev,
+ struct ttm_buffer_object *bo,
+ unsigned long size,
+ enum ttm_bo_type type,
+ uint32_t page_alignment,
+ struct file *persistent_swap_storage,
+ size_t acc_size,
+ struct sg_table *sg,
+ struct reservation_object *resv,
+ void (*destroy) (struct ttm_buffer_object *));
+
+/**
* ttm_bo_init
*
* @bdev: Pointer to a ttm_bo_device struct.
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