i965g: add lots of error checks and early returns

Any allocation that may fail should be checked, and propogate the
error upwards.  At the highest level we will flush batch and retry.

This is an alternate strategy to what the original DRI driver did of
attempting to flush batch from the lowest levels (eg inside
BEGIN_BATCH).  The trouble with that strategy was that flushes could
occur at unexpected times, and additionally there was a need for a
wierd notification mechanism to propogate the 'lost context' state
back up to higher levels.

Propogating the errors directly gives us a lot of flexibility how to
deal with these states, at the expense of a lot more checking in the
code.

Will add some sanity checks later to make sure that out-of-memory
conditions are properly escalated and not lost halfway up the stack.

1 files changed, 10 insertions, 9 deletions

diff --git a/src/gallium/drivers/i965/brw_batchbuffer.c b/src/gallium/drivers/i965/brw_batchbuffer.c
index ca612e5ed0..e5f73bd6a3 100644
--- a/src/gallium/drivers/i965/brw_batchbuffer.c
+++ b/src/gallium/drivers/i965/brw_batchbuffer.c
@@ -38,17 +38,17 @@
 #define USE_MALLOC_BUFFER 1
 #define ALWAYS_EMIT_MI_FLUSH 1
 
-void
+enum pipe_error
 brw_batchbuffer_reset(struct brw_batchbuffer *batch)
 {
-   if (batch->buf) {
-      batch->sws->bo_unreference(batch->buf);
-      batch->buf = NULL;
-   }
+   enum pipe_error ret;
 
-   batch->buf = batch->sws->bo_alloc(batch->sws,
-				     BRW_BUFFER_TYPE_BATCH,
-				     BRW_BATCH_SIZE, 4096);
+   ret = batch->sws->bo_alloc( batch->sws,
+                               BRW_BUFFER_TYPE_BATCH,
+                               BRW_BATCH_SIZE, 4096,
+                               &batch->buf );
+   if (ret)
+      return ret;
 
    if (batch->malloc_buffer)
       batch->map = batch->malloc_buffer;
@@ -59,6 +59,7 @@ brw_batchbuffer_reset(struct brw_batchbuffer *batch)
 
    batch->size = BRW_BATCH_SIZE;
    batch->ptr = batch->map;
+   return PIPE_OK;
 }
 
 struct brw_batchbuffer *
@@ -91,7 +92,7 @@ brw_batchbuffer_free(struct brw_batchbuffer *batch)
       batch->map = NULL;
    }
 
-   batch->sws->bo_unreference(batch->buf);
+   bo_reference(&batch->buf, NULL);
    FREE(batch);
 }