From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri, 27 Mar 2015 11:02:10 +0000 (+0000)
Subject: drm/i915: Skip allocating shadow batch for 0-length batches
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=743e78c1d726d875b98ff9689cc77c4d3d5d9ae2;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

drm/i915: Skip allocating shadow batch for 0-length batches

Since

commit 17cabf571e50677d980e9ab2a43c5f11213003ae
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Wed Jan 14 11:20:57 2015 +0000

    drm/i915: Trim the command parser allocations

we may then try to allocate a zero-sized object and attempt to extract
its pages. Understandably this fails.

Testcase: igt/gem_exec_nop #ivb,byt,hsw
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 43335de0f713..a3190e793ed4 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1547,7 +1547,7 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
 		goto err;
 	}
 
-	if (i915_needs_cmd_parser(ring)) {
+	if (i915_needs_cmd_parser(ring) && args->batch_len) {
 		batch_obj = i915_gem_execbuffer_parse(ring,
 						      &shadow_exec_entry,
 						      eb,