From: Eric Anholt <eric@anholt.net>
Date: Thu, 20 Sep 2007 18:41:25 +0000 (-0700)
Subject: Uniquely validate the batchbuffer-referenced buffers.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=c1ecc383204914567c6de1587d7b9559ec72ce6e;p=mesa.git

Uniquely validate the batchbuffer-referenced buffers.

Otherwise, for multiple references by the batchbuffer, the kernel would see
the buffer already on the unfenced list and wait for it to leave the list
before continuing, leading to hanging and eventual -EBUSY.
---

diff --git a/src/mesa/drivers/dri/i915tex/intel_batchbuffer.c b/src/mesa/drivers/dri/i915tex/intel_batchbuffer.c
index 5515d6c235a..8ee48b5a689 100644
--- a/src/mesa/drivers/dri/i915tex/intel_batchbuffer.c
+++ b/src/mesa/drivers/dri/i915tex/intel_batchbuffer.c
@@ -116,6 +116,14 @@ intel_batchbuffer_free(struct intel_batchbuffer *batch)
    free(batch);
 }
 
+static int
+relocation_sort(const void *a_in, const void *b_in) {
+   const struct buffer_reloc *a = a_in, *b = b_in;
+
+   return (intptr_t)a->buf < (intptr_t)b->buf ? -1 : 1;
+}
+
+
 /* TODO: Push this whole function into bufmgr.
  */
 static void
@@ -132,13 +140,49 @@ do_flush_locked(struct intel_batchbuffer *batch,
    assert(batch->buf->virtual != NULL);
    ptr = batch->buf->virtual;
 
+   /* Sort our relocation list in terms of referenced buffer pointer.
+    * This lets us uniquely validate the buffers with the sum of all the flags,
+    * while avoiding O(n^2) on number of relocations.
+    */
+   qsort(batch->reloc, batch->nr_relocs, sizeof(batch->reloc[0]),
+	 relocation_sort);
+
+   /* Perform the necessary validations of buffers, and enter the relocations
+    * in the batchbuffer.
+    */
    for (i = 0; i < batch->nr_relocs; i++) {
       struct buffer_reloc *r = &batch->reloc[i];
 
       if (r->validate_flags & DRM_BO_FLAG_WRITE)
 	 performed_rendering = GL_TRUE;
 
-      dri_bo_validate(r->buf, r->validate_flags);
+      /* If this is the first time we've seen this buffer in the relocation
+       * list, figure out our flags and validate it.
+       */
+      if (i == 0 || batch->reloc[i - 1].buf != r->buf) {
+	 uint32_t validate_flags;
+	 int j, ret;
+
+	 /* Accumulate the flags we need for validating this buffer. */
+	 validate_flags = r->validate_flags;
+	 for (j = i + 1; j < batch->nr_relocs; j++) {
+	    if (batch->reloc[j].buf != r->buf)
+	       break;
+	    validate_flags |= batch->reloc[j].validate_flags;
+	 }
+
+	 /* Validate.  If we fail, fence to clear the unfenced list and bail
+	  * out.
+	  */
+	 ret = dri_bo_validate(r->buf, validate_flags);
+	 if (ret != 0) {
+	    dri_bo_unmap(batch->buf);
+	    fo = dri_fence_validated(intel->intelScreen->bufmgr,
+				     "batchbuffer failure fence", GL_TRUE);
+	    dri_fence_unreference(fo);
+	    goto done;
+	 }
+      }
       ptr[r->offset / 4] = r->buf->offset + r->delta;
       dri_bo_unreference(r->buf);
    }
@@ -193,6 +237,7 @@ do_flush_locked(struct intel_batchbuffer *batch,
       intel->vtbl.lost_hardware(intel);
    }
 
+done:
    if (INTEL_DEBUG & DEBUG_BATCH) {
       dri_bo_map(batch->buf, GL_FALSE);
       intel_decode(ptr, used / 4, batch->buf->offset);