Commit d9c148cf authored Nov 14, 2019 by Tomi Valkeinen

drm/omap: fix dma_addr refcounting



cec4fa75 ("drm/omap: use refcount API to
track the number of users of dma_addr") changed omap_gem.c to use
refcounting API to track dma_addr uses.  However, the driver only tracks
the refcounts for non-contiguous buffers, and the patch didn't fully
take this in account.

After the patch, the driver always decreased refcount in omap_gem_unpin,
instead of decreasing the refcount only for non-contiguous buffers. This
leads to refcounting mismatch.

As for the contiguous cases the refcount is never increased, fix this
issue by returning from omap_gem_unpin if the buffer being unpinned is
contiguous.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191114080343.30704-1-tomi.valkeinen@ti.com


Fixes: cec4fa75 ("drm/omap: use refcount API to track the number of users of dma_addr")
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

parent d6d07ca1

drivers/gpu/drm/omapdrm/omap_gem.c

+4 −0

Original line number	Original line	Diff line number	Diff line
	@@ -843,9 +843,13 @@ fail:
	*/		*/
	static void omap_gem_unpin_locked(struct drm_gem_object *obj)		static void omap_gem_unpin_locked(struct drm_gem_object *obj)
	{		{
			struct omap_drm_private *priv = obj->dev->dev_private;
	struct omap_gem_object *omap_obj = to_omap_bo(obj);		struct omap_gem_object *omap_obj = to_omap_bo(obj);
	int ret;		int ret;

			if (omap_gem_is_contiguous(omap_obj) \|\| !priv->has_dmm)
			return;

	if (refcount_dec_and_test(&omap_obj->dma_addr_cnt)) {		if (refcount_dec_and_test(&omap_obj->dma_addr_cnt)) {
	ret = tiler_unpin(omap_obj->block);		ret = tiler_unpin(omap_obj->block);
	if (ret) {		if (ret) {

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