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Commit 4ed7e224 authored by Sinclair Yeh's avatar Sinclair Yeh
Browse files

drm/vmwgfx: Check pin count before attempting to move a buffer 



In certain scenarios, e.g. when fbdev is enabled, we can get into
a situation where a vmw_framebuffer_pin() is called on a buffer
that is already pinned.

When this happens, ttm_bo_validate() will unintentially remove the
TTM_PL_FLAG_NO_EVICT flag, thus unpinning it, and leaving no way
to actually pin the buffer again.

To prevent this, if a buffer is already pinned, then instead of
calling ttm_bo_validate(), just make sure the proposed placement is
compatible with the existing placement.

Signed-off-by: default avatarSinclair Yeh <syeh@vmware.com>
Reviewed-by: default avatarThomas Hellstrom <thellstrom@vmware.com>
Cc: <stable@vger.kernel.org>
---
This is the 2nd patch in a 3-patch series to fix a console black
screen issue on Ubuntu 16.04 server.  This fixes a BUG_ON()
condition where a pinned buffer gets accidentally put onto the
LRU list.
parent 94477bff

drivers/gpu/drm/vmwgfx/vmwgfx_dmabuf.c

+22 −3
Original line number Diff line number Diff line
@@ -49,6 +49,7 @@ int vmw_dmabuf_pin_in_placement(struct vmw_private *dev_priv, 
{

	struct ttm_buffer_object *bo = &buf->base;

	int ret;

	uint32_t new_flags;



	ret = ttm_write_lock(&dev_priv->reservation_sem, interruptible);

	if (unlikely(ret != 0))
@@ -60,7 +61,12 @@ int vmw_dmabuf_pin_in_placement(struct vmw_private *dev_priv, 
	if (unlikely(ret != 0))

		goto err;



	if (buf->pin_count > 0)

		ret = ttm_bo_mem_compat(placement, &bo->mem,

					&new_flags) == true ? 0 : -EINVAL;

	else

		ret = ttm_bo_validate(bo, placement, interruptible, false);



	if (!ret)

		vmw_bo_pin_reserved(buf, true);
@@ -91,6 +97,7 @@ int vmw_dmabuf_pin_in_vram_or_gmr(struct vmw_private *dev_priv, 
{

	struct ttm_buffer_object *bo = &buf->base;

	int ret;

	uint32_t new_flags;



	ret = ttm_write_lock(&dev_priv->reservation_sem, interruptible);

	if (unlikely(ret != 0))
@@ -102,6 +109,12 @@ int vmw_dmabuf_pin_in_vram_or_gmr(struct vmw_private *dev_priv, 
	if (unlikely(ret != 0))

		goto err;



	if (buf->pin_count > 0) {

		ret = ttm_bo_mem_compat(&vmw_vram_gmr_placement, &bo->mem,

					&new_flags) == true ? 0 : -EINVAL;

		goto out_unreserve;

	}



	ret = ttm_bo_validate(bo, &vmw_vram_gmr_placement, interruptible,

			      false);

	if (likely(ret == 0) || ret == -ERESTARTSYS)
@@ -161,6 +174,7 @@ int vmw_dmabuf_pin_in_start_of_vram(struct vmw_private *dev_priv, 
	struct ttm_placement placement;

	struct ttm_place place;

	int ret = 0;

	uint32_t new_flags;



	place = vmw_vram_placement.placement[0];

	place.lpfn = bo->num_pages;
@@ -185,9 +199,14 @@ int vmw_dmabuf_pin_in_start_of_vram(struct vmw_private *dev_priv, 
	 */

	if (bo->mem.mem_type == TTM_PL_VRAM &&

	    bo->mem.start < bo->num_pages &&

	    bo->mem.start > 0)

	    bo->mem.start > 0 &&

	    buf->pin_count == 0)

		(void) ttm_bo_validate(bo, &vmw_sys_placement, false, false);



	if (buf->pin_count > 0)

		ret = ttm_bo_mem_compat(&placement, &bo->mem,

					&new_flags) == true ? 0 : -EINVAL;

	else

		ret = ttm_bo_validate(bo, &placement, interruptible, false);



	/* For some reason we didn't end up at the start of vram */