[PATCH weston 5/9] compositor-drm: drm_property_info_free() must reset

Pekka Paalanen ppaalanen at gmail.com
Fri Feb 9 13:07:23 UTC 2018

From: Pekka Paalanen <pekka.paalanen at collabora.co.uk>

This function needs to reset the structures to NULL, otherwise it is not
possible to re-use a once "freed" property info array.

Being able to re-use an array is useful when the memory allocation and
array lifetimes do not match. A specific example is drm_output that is
changed to allocate the CRTC on enable() and deallocate it on disable().
A drm_output might be enabled and disabled multiple times.

Signed-off-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
 libweston/compositor-drm.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/libweston/compositor-drm.c b/libweston/compositor-drm.c
index 4b505707..23ffb005 100644
--- a/libweston/compositor-drm.c
+++ b/libweston/compositor-drm.c
@@ -721,7 +721,9 @@ drm_property_info_populate(struct drm_backend *b,
  * Free DRM property information
- * Frees all memory associated with a DRM property info array.
+ * Frees all memory associated with a DRM property info array and zeroes
+ * it out, leaving it usable for a further drm_property_info_update() or
+ * drm_property_info_free().
  * @param info DRM property info array
  * @param num_props Number of entries in array to free
@@ -733,6 +735,8 @@ drm_property_info_free(struct drm_property_info *info, int num_props)
 	for (i = 0; i < num_props; i++)
+	memset(info, 0, sizeof(*info) * num_props);
 static void

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