Am 20.08.19 um 17:21 schrieb Daniel Vetter:
> On Tue, Aug 20, 2019 at 5:16 PM Koenig, Christian
> <Christian.Koenig@xxxxxxx> wrote:
>> Am 20.08.19 um 16:53 schrieb Daniel Vetter:
>>> With nouveau fixed all ttm-using drives have the correct nesting of
>>> mmap_sem vs dma_resv, and we can just lock the buffer.
>>>
>>> Assuming I didn't screw up anything with my audit of course.
>>>
>>> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
>>> Cc: Christian Koenig <christian.koenig@xxxxxxx>
>>> Cc: Huang Rui <ray.huang@xxxxxxx>
>>> Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx>
>>> Cc: "VMware Graphics" <linux-graphics-maintainer@xxxxxxxxxx>
>>> Cc: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
>> Yes, please. But one more point: you can now remove bo->wu_mutex as well!
> Ah right totally forgot about that in my enthusiasm after all the
> auditing and fixing nouveau.
>
>> Apart from that Reviewed-by: Christian König <christian.koenig@xxxxxxx>
> Thanks, I already respun the patches, so will be in the next version.
> Can you pls also give this a spin on the amdgpu CI, just to make sure
> it's all fine? With full lockdep ofc. And then reply with a t-b.
I can ask for this on our call tomorrow, but I fear our CI
infrastructure is not ready yet.
Christian.
>
> Thanks, Daniel
>>> ---
>>> drivers/gpu/drm/ttm/ttm_bo.c | 34 ---------------------------------
>>> drivers/gpu/drm/ttm/ttm_bo_vm.c | 26 +------------------------
>>> include/drm/ttm/ttm_bo_api.h | 1 -
>>> 3 files changed, 1 insertion(+), 60 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
>>> index 20ff56f27aa4..a952dd624b06 100644
>>> --- a/drivers/gpu/drm/ttm/ttm_bo.c
>>> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
>>> @@ -1954,37 +1954,3 @@ void ttm_bo_swapout_all(struct ttm_bo_device *bdev)
>>> ;
>>> }
>>> EXPORT_SYMBOL(ttm_bo_swapout_all);
>>> -
>>> -/**
>>> - * ttm_bo_wait_unreserved - interruptible wait for a buffer object to become
>>> - * unreserved
>>> - *
>>> - * @bo: Pointer to buffer
>>> - */
>>> -int ttm_bo_wait_unreserved(struct ttm_buffer_object *bo)
>>> -{
>>> - int ret;
>>> -
>>> - /*
>>> - * In the absense of a wait_unlocked API,
>>> - * Use the bo::wu_mutex to avoid triggering livelocks due to
>>> - * concurrent use of this function. Note that this use of
>>> - * bo::wu_mutex can go away if we change locking order to
>>> - * mmap_sem -> bo::reserve.
>>> - */
>>> - ret = mutex_lock_interruptible(&bo->wu_mutex);
>>> - if (unlikely(ret != 0))
>>> - return -ERESTARTSYS;
>>> - if (!dma_resv_is_locked(bo->base.resv))
>>> - goto out_unlock;
>>> - ret = dma_resv_lock_interruptible(bo->base.resv, NULL);
>>> - if (ret == -EINTR)
>>> - ret = -ERESTARTSYS;
>>> - if (unlikely(ret != 0))
>>> - goto out_unlock;
>>> - dma_resv_unlock(bo->base.resv);
>>> -
>>> -out_unlock:
>>> - mutex_unlock(&bo->wu_mutex);
>>> - return ret;
>>> -}
>>> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
>>> index 76eedb963693..505e1787aeea 100644
>>> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
>>> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
>>> @@ -125,31 +125,7 @@ static vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
>>> &bdev->man[bo->mem.mem_type];
>>> struct vm_area_struct cvma;
>>>
>>> - /*
>>> - * Work around locking order reversal in fault / nopfn
>>> - * between mmap_sem and bo_reserve: Perform a trylock operation
>>> - * for reserve, and if it fails, retry the fault after waiting
>>> - * for the buffer to become unreserved.
>>> - */
>>> - if (unlikely(!dma_resv_trylock(bo->base.resv))) {
>>> - if (vmf->flags & FAULT_FLAG_ALLOW_RETRY) {
>>> - if (!(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
>>> - ttm_bo_get(bo);
>>> - up_read(&vmf->vma->vm_mm->mmap_sem);
>>> - (void) ttm_bo_wait_unreserved(bo);
>>> - ttm_bo_put(bo);
>>> - }
>>> -
>>> - return VM_FAULT_RETRY;
>>> - }
>>> -
>>> - /*
>>> - * If we'd want to change locking order to
>>> - * mmap_sem -> bo::reserve, we'd use a blocking reserve here
>>> - * instead of retrying the fault...
>>> - */
>>> - return VM_FAULT_NOPAGE;
>>> - }
>>> + dma_resv_lock(bo->base.resv, NULL);
>>>
>>> /*
>>> * Refuse to fault imported pages. This should be handled
>>> diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
>>> index 43c4929a2171..6b50e624e3e2 100644
>>> --- a/include/drm/ttm/ttm_bo_api.h
>>> +++ b/include/drm/ttm/ttm_bo_api.h
>>> @@ -765,7 +765,6 @@ ssize_t ttm_bo_io(struct ttm_bo_device *bdev, struct file *filp,
>>> int ttm_bo_swapout(struct ttm_bo_global *glob,
>>> struct ttm_operation_ctx *ctx);
>>> void ttm_bo_swapout_all(struct ttm_bo_device *bdev);
>>> -int ttm_bo_wait_unreserved(struct ttm_buffer_object *bo);
>>>
>>> /**
>>> * ttm_bo_uses_embedded_gem_object - check if the given bo uses the
>
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