On Thu, Dec 22, 2016 at 08:36:28AM +0000, Chris Wilson wrote:
A simple assert to ensure that we don't overflow start + size when initialising the drm_mm, or its scanner.
In future, we may want to switch to tracking the value of ranges (rather than size) so that we can cover the full u64, for example like resource tracking.
Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Reviewed-by: Joonas Lahtinen joonas.lahtinen@linux.intel.com
drivers/gpu/drm/drm_mm.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c index e0419cf09bbb..b80305484124 100644 --- a/drivers/gpu/drm/drm_mm.c +++ b/drivers/gpu/drm/drm_mm.c @@ -729,6 +729,8 @@ void drm_mm_init_scan(struct drm_mm *mm, u64 alignment, unsigned long color) {
- DRM_MM_BUG_ON(!size);
General thought: Do we/should we have testcases for these negative checks? Adding a drm_mm_test_mode or similar that DRM_MM_BUG_ON checks before calling BUG_ON, and using that in drm_mm_selftest.ko would make that work.
Maybe we could even do that somewhat generically in drm_selftect code. Since we can't continue without causing real havoc a possible solution would be to just exit the current thread. And provdide a drm_selftest.c wrapper which sets this option, runs the testcode in a separate thread and then checks that we've exited through DRM_MM_BUG_ON.
Just as an idea really. -Daniel
- mm->scan_color = color; mm->scan_alignment = alignment; mm->scan_size = size;
@@ -764,6 +766,9 @@ void drm_mm_init_scan_with_range(struct drm_mm *mm, u64 start, u64 end) {
- DRM_MM_BUG_ON(start >= end);
- DRM_MM_BUG_ON(!size || size > end - start);
- mm->scan_color = color; mm->scan_alignment = alignment; mm->scan_size = size;
@@ -882,6 +887,8 @@ EXPORT_SYMBOL(drm_mm_scan_remove_block); */ void drm_mm_init(struct drm_mm *mm, u64 start, u64 size) {
- DRM_MM_BUG_ON(start + size <= start);
- INIT_LIST_HEAD(&mm->hole_stack); mm->scanned_blocks = 0;
-- 2.11.0
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