[Mesa-dev] [PATCH v2] util/ralloc: Remove double zero'ing of rzalloc buffers

[Jordan Justen]

Juha-Pekka found this back in May 2015:
<1430915727-28677-1-git-send-email-juhapekka.heikkila at gmail.com>

>From the discussion, obviously it would be preferable to make
ralloc_size no longer return zeroed memory, but Juha-Pekka found that
it would break Mesa.

In <56AF1C57.2030904 at gmail.com>, Juha-Pekka mentioned that patches
exist to fix i965 when ralloc_size is fixed to not zero memory, but
the patches have not made their way to mesa-dev yet.

For now, let's stop doing the double zeroing of rzalloc buffers.

v2:
 * Move ralloc_size code to rzalloc_size, and add a comment as
   suggested by Ken.

Signed-off-by: Jordan Justen <jordan.l.justen at intel.com>
Cc: Juha-Pekka Heikkila <juhapekka.heikkila at gmail.com>
Cc: Kenneth Graunke <kenneth at whitecape.org>
---
 src/util/ralloc.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/src/util/ralloc.c b/src/util/ralloc.c
index 6d4032b..9526011 100644
--- a/src/util/ralloc.c
+++ b/src/util/ralloc.c
@@ -110,6 +110,18 @@ ralloc_context(const void *ctx)
 void *
 ralloc_size(const void *ctx, size_t size)
 {
+   /* ralloc_size was originally implemented using calloc, which meant some
+    * code accidentally relied on its zero filling behavior.
+    *
+    * TODO: Make ralloc_size not zero fill memory, and cleanup any code that
+    * should instead be using rzalloc.
+    */
+   return rzalloc_size(ctx, size);
+}
+
+void *
+rzalloc_size(const void *ctx, size_t size)
+{
    void *block = calloc(1, size + sizeof(ralloc_header));
    ralloc_header *info;
    ralloc_header *parent;
@@ -128,15 +140,6 @@ ralloc_size(const void *ctx, size_t size)
    return PTR_FROM_HEADER(info);
 }
 
-void *
-rzalloc_size(const void *ctx, size_t size)
-{
-   void *ptr = ralloc_size(ctx, size);
-   if (likely(ptr != NULL))
-      memset(ptr, 0, size);
-   return ptr;
-}
-
 /* helper function - assumes ptr != NULL */
 static void *
 resize(void *ptr, size_t size)
-- 
2.8.1