Mesa (master): i965: Allocate shadow batches to explicitly be the BO size.

[Kenneth Graunke]

Module: Mesa
Branch: master
Commit: 5c049718318bfd9957aaa8f232d40286e101f02f
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=5c049718318bfd9957aaa8f232d40286e101f02f

Author: Kenneth Graunke <kenneth at whitecape.org>
Date:   Fri Apr 13 15:35:56 2018 -0700

i965: Allocate shadow batches to explicitly be the BO size.

This unfortunately makes it malloc/realloc on every new batch, rather
than once at startup.  But it ensures that the shadow buffer's size will
absolutely match the BO size.  Otherwise, as we tune BATCH_SZ/STATE_SZ
or bufmgr cache bucket sizes, we may get a BO size that's rounded up,
and fail to allocate the shadow buffer large enough.

This doesn't fix any bugs today, as BATCH_SZ/STATE_SZ are the size of
a cache bucket, but it's better to be safe than sorry.

Reported-by: James Xiong <james.xiong at intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>

---

 src/mesa/drivers/dri/i965/intel_batchbuffer.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/intel_batchbuffer.c b/src/mesa/drivers/dri/i965/intel_batchbuffer.c
index d745c2a311..b511be3741 100644
--- a/src/mesa/drivers/dri/i965/intel_batchbuffer.c
+++ b/src/mesa/drivers/dri/i965/intel_batchbuffer.c
@@ -107,15 +107,11 @@ intel_batchbuffer_init(struct brw_context *brw)
 
    batch->use_shadow_copy = !devinfo->has_llc;
 
-   if (batch->use_shadow_copy) {
-      batch->batch.map = malloc(BATCH_SZ);
-      batch->map_next = batch->batch.map;
-      batch->state.map = malloc(STATE_SZ);
-   }
-
    init_reloc_list(&batch->batch_relocs, 250);
    init_reloc_list(&batch->state_relocs, 250);
 
+   batch->batch.map = NULL;
+   batch->state.map = NULL;
    batch->exec_count = 0;
    batch->exec_array_size = 100;
    batch->exec_bos =
@@ -196,7 +192,9 @@ recreate_growing_buffer(struct brw_context *brw,
    grow->partial_bo_map = NULL;
    grow->partial_bytes = 0;
 
-   if (!batch->use_shadow_copy)
+   if (batch->use_shadow_copy)
+      grow->map = realloc(grow->map, grow->bo->size);
+   else
       grow->map = brw_bo_map(brw, grow->bo, MAP_READ | MAP_WRITE);
 }