Re: [PATCH] drm/i915: Fix possible uninitialized variable in parallel extension

[Lucas De Marchi]

On Sat, Dec 18, 2021 at 04:19:09PM -0800, Matthew Brost wrote:

'prev_engine' was declared inside the output loop and checked in the
inner after at least 1 pass of either loop. The variable should be
declared outside both loops as it needs to be persistent across the
entire loop structure.

Fixes: e5e32171a2cf ("drm/i915/guc: Connect UAPI to GuC multi-lrc interface")
Signed-off-by: Matthew Brost 



Reviewed-by: Lucas De Marchi 

thanks
Lucas De Marchi

[PATCH] drm/i915: Fix possible uninitialized variable in parallel extension

[Matthew Brost]

'prev_engine' was declared inside the output loop and checked in the
inner after at least 1 pass of either loop. The variable should be
declared outside both loops as it needs to be persistent across the
entire loop structure.

Fixes: e5e32171a2cf ("drm/i915/guc: Connect UAPI to GuC multi-lrc interface")
Signed-off-by: Matthew Brost 
---
 drivers/gpu/drm/i915/gem/i915_gem_context.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c 
b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index 347dab952e90..97d2ac22ae55 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -564,6 +564,7 @@ set_proto_ctx_engines_parallel_submit(struct 
i915_user_extension __user *base,
container_of_user(base, typeof(*ext), base);
const struct set_proto_ctx_engines *set = data;
struct drm_i915_private *i915 = set->i915;
+   struct i915_engine_class_instance prev_engine;
u64 flags;
int err = 0, n, i, j;
u16 slot, width, num_siblings;
@@ -629,7 +630,6 @@ set_proto_ctx_engines_parallel_submit(struct 
i915_user_extension __user *base,
/* Create contexts / engines */
for (i = 0; i < width; ++i) {
intel_engine_mask_t current_mask = 0;
-   struct i915_engine_class_instance prev_engine;
 
for (j = 0; j < num_siblings; ++j) {
struct i915_engine_class_instance ci;
-- 
2.33.1