drm/i915: Add a test that we terminate the trimmed sgtable as expected

ickle · ickle · commit c2dc6cc946aa · 2016-12-20T12:31:52.000Z
In commit 0c40ce1 ("drm/i915: Trim the object sg table"), we expect to copy exactly orig_st->nents across and allocate the table thusly. The copy loop should therefore end with the new_sg being NULL. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161219124346.550-2-chris@chris-wilson.co.uk Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
@@ -2333,6 +2333,7 @@ static void i915_sg_trim(struct sg_table *orig_st)
 		/* called before being DMA mapped, no need to copy sg->dma_* */
 		new_sg = sg_next(new_sg);
 	}
+	GEM_BUG_ON(new_sg); /* Should walk exactly nents and hit the end */
 
 	sg_free_table(orig_st);
 

Original file line number	Diff line number	Diff line change
`@@ -2333,6 +2333,7 @@ static void i915_sg_trim(struct sg_table *orig_st)`
`2333`	`2333`	`/* called before being DMA mapped, no need to copy sg->dma_* */`
`2334`	`2334`	`new_sg = sg_next(new_sg);`
`2335`	`2335`	`}`
	`2336`	`+ GEM_BUG_ON(new_sg); /* Should walk exactly nents and hit the end */`
`2336`	`2337`
`2337`	`2338`	`sg_free_table(orig_st);`
`2338`	`2339`