Commit 6b1ce0a2 authored by Daniel Vetter's avatar Daniel Vetter
Browse files

drm/ttm: remove ttm_bo_wait_unreserved 



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.

v2:
- Dont forget wu_mutex (Christian König)
- Keep the mmap_sem-less wait optimization (Thomas)
- Use _lock_interruptible to be good citizens (Thomas)

v3: Rebase over fault handler helperification.

Reviewed-by: Christian König <christian.koenig@amd.com> (v2)
Reviewed-by: Thomas Hellström <thellstrom@vmware.com> (v2)
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@intel.com>
Cc: Christian Koenig <christian.koenig@amd.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: "VMware Graphics" <linux-graphics-maintainer@vmware.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191104173801.2972-3-daniel.vetter@ffwll.ch
parent 03e0d26f

drivers/gpu/drm/ttm/ttm_bo.c

+0 −36
Original line number Diff line number Diff line
@@ -161,7 +161,6 @@ static void ttm_bo_release_list(struct kref *list_kref) 
	dma_fence_put(bo->moving);

	if (!ttm_bo_uses_embedded_gem_object(bo))

		dma_resv_fini(&bo->base._resv);

	mutex_destroy(&bo->wu_mutex);

	bo->destroy(bo);

	ttm_mem_global_free(&ttm_mem_glob, acc_size);

}
@@ -1291,7 +1290,6 @@ int ttm_bo_init_reserved(struct ttm_bo_device *bdev, 
	INIT_LIST_HEAD(&bo->ddestroy);

	INIT_LIST_HEAD(&bo->swap);

	INIT_LIST_HEAD(&bo->io_reserve_lru);

	mutex_init(&bo->wu_mutex);

	bo->bdev = bdev;

	bo->type = type;

	bo->num_pages = num_pages;
@@ -1895,37 +1893,3 @@ void ttm_bo_swapout_all(struct ttm_bo_device *bdev) 
	while (ttm_bo_swapout(&ttm_bo_glob, &ctx) == 0);

}

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;

}

drivers/gpu/drm/ttm/ttm_bo_util.c

+0 −1
Original line number Diff line number Diff line
@@ -504,7 +504,6 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo, 
	INIT_LIST_HEAD(&fbo->base.lru);

	INIT_LIST_HEAD(&fbo->base.swap);

	INIT_LIST_HEAD(&fbo->base.io_reserve_lru);

	mutex_init(&fbo->base.wu_mutex);

	fbo->base.moving = NULL;

	drm_vma_node_reset(&fbo->base.base.vma_node);

drivers/gpu/drm/ttm/ttm_bo_vm.c

+5 −13
Original line number Diff line number Diff line
@@ -128,29 +128,21 @@ static unsigned long ttm_bo_io_mem_pfn(struct ttm_buffer_object *bo, 
vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,

			     struct vm_fault *vmf)

{

	/*

	 * 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);

				if (!dma_resv_lock_interruptible(bo->base.resv,

								 NULL))

					dma_resv_unlock(bo->base.resv);

				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...

		 */

		if (dma_resv_lock_interruptible(bo->base.resv, NULL))

			return VM_FAULT_NOPAGE;

	}

include/drm/ttm/ttm_bo_api.h

+0 −4
Original line number Diff line number Diff line
@@ -154,7 +154,6 @@ struct ttm_tt; 
 * @offset: The current GPU offset, which can have different meanings

 * depending on the memory type. For SYSTEM type memory, it should be 0.

 * @cur_placement: Hint of current placement.

 * @wu_mutex: Wait unreserved mutex.

 *

 * Base class for TTM buffer object, that deals with data placement and CPU

 * mappings. GPU mappings are really up to the driver, but for simpler GPUs
@@ -222,8 +221,6 @@ struct ttm_buffer_object { 
	uint64_t offset; /* GPU address space is independent of CPU word size */



	struct sg_table *sg;



	struct mutex wu_mutex;

};



/**
@@ -707,7 +704,6 @@ 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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