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, 34 insertions, 24 deletions

diff --git a/src/gallium/drivers/i965/brw_vs_state.c b/src/gallium/drivers/i965/brw_vs_state.c
index 26d5d005fa..22a4d7f01b 100644
--- a/src/gallium/drivers/i965/brw_vs_state.c
+++ b/src/gallium/drivers/i965/brw_vs_state.c
@@ -78,11 +78,13 @@ vs_unit_populate_key(struct brw_context *brw, struct brw_vs_unit_key *key)
    }
 }
 
-static struct brw_winsys_buffer *
-vs_unit_create_from_key(struct brw_context *brw, struct brw_vs_unit_key *key)
+static enum pipe_error
+vs_unit_create_from_key(struct brw_context *brw, 
+                        struct brw_vs_unit_key *key,
+                        struct brw_winsys_buffer **bo_out)
 {
+   enum pipe_error ret;
    struct brw_vs_unit_state vs;
-   struct brw_winsys_buffer *bo;
    int chipset_max_threads;
 
    memset(&vs, 0, sizeof(vs));
@@ -141,38 +143,46 @@ vs_unit_create_from_key(struct brw_context *brw, struct brw_vs_unit_key *key)
     */
    vs.vs6.vs_enable = 1;
 
-   bo = brw_upload_cache(&brw->cache, BRW_VS_UNIT,
-			 key, sizeof(*key),
-			 &brw->vs.prog_bo, 1,
-			 &vs, sizeof(vs),
-			 NULL, NULL);
+   ret = brw_upload_cache(&brw->cache, BRW_VS_UNIT,
+                          key, sizeof(*key),
+                          &brw->vs.prog_bo, 1,
+                          &vs, sizeof(vs),
+                          NULL, NULL,
+                          bo_out);
+   if (ret)
+      return ret;
 
    /* Emit VS program relocation */
-   brw->sws->bo_emit_reloc(bo,
-			   BRW_USAGE_STATE,
-			   vs.thread0.grf_reg_count << 1,
-			   offsetof(struct brw_vs_unit_state, thread0),
-			   brw->vs.prog_bo);
-
-   return bo;
+   ret = brw->sws->bo_emit_reloc(*bo_out,
+                                 BRW_USAGE_STATE,
+                                 vs.thread0.grf_reg_count << 1,
+                                 offsetof(struct brw_vs_unit_state, thread0),
+                                 brw->vs.prog_bo);
+   if (ret)
+      return ret;
+
+   return PIPE_OK;
 }
 
 static int prepare_vs_unit(struct brw_context *brw)
 {
    struct brw_vs_unit_key key;
+   enum pipe_error ret;
 
    vs_unit_populate_key(brw, &key);
 
-   brw->sws->bo_unreference(brw->vs.state_bo);
-   brw->vs.state_bo = brw_search_cache(&brw->cache, BRW_VS_UNIT,
-				       &key, sizeof(key),
-				       &brw->vs.prog_bo, 1,
-				       NULL);
-   if (brw->vs.state_bo == NULL) {
-      brw->vs.state_bo = vs_unit_create_from_key(brw, &key);
-   }
+   if (brw_search_cache(&brw->cache, BRW_VS_UNIT,
+                        &key, sizeof(key),
+                        &brw->vs.prog_bo, 1,
+                        NULL,
+                        &brw->vs.state_bo))
+      return PIPE_OK;
+
+   ret = vs_unit_create_from_key(brw, &key, &brw->vs.state_bo);
+   if (ret)
+      return ret;
 
-   return 0;
+   return PIPE_OK;
 }
 
 const struct brw_tracked_state brw_vs_unit = {