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

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

[Chris Wilson]

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>
---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 6408d7581124..b3afb673d356 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1562,7 +1562,7 @@ 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,
-- 
2.1.4

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Re: [PATCH] drm/i915: Skip allocating shadow batch for 0-length batches

[shuang.he]

Tested-By: PRC QA PRTS (Patch Regression Test System Contact: shuang.he@intel.com)
Task id: 6036
-------------------------------------Summary-------------------------------------
Platform          Delta          drm-intel-nightly          Series Applied
PNV                 -1              275/275              274/275
ILK                                  303/303              303/303
SNB                                  304/304              304/304
IVB                                  339/339              339/339
BYT                                  287/287              287/287
HSW                                  361/361              361/361
BDW                                  310/310              310/310
-------------------------------------Detailed-------------------------------------
Platform  Test                                drm-intel-nightly          Series Applied
 PNV  igt@gem_userptr_blits@minor-unsync-normal      DMESG_WARN(1)PASS(2)      DMESG_WARN(1)PASS(1)
Note: You need to pay more attention to line start with '*'
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