2021-08-24 22:56:37

by Nathan Chancellor

Subject: [PATCH 1/3] drm/i915/selftests: Do not use import_obj uninitialized

Clang warns a couple of times:

drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c:63:6: warning:
variable 'import_obj' is used uninitialized whenever 'if' condition is
true [-Wsometimes-uninitialized]
if (import != &obj->base) {
^~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c:80:22: note:
uninitialized use occurs here
i915_gem_object_put(import_obj);
^~~~~~~~~~
drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c:63:2: note: remove
the 'if' if its condition is always false
if (import != &obj->base) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c:38:46: note:
initialize the variable 'import_obj' to silence this warning
struct drm_i915_gem_object *obj, *import_obj;
^
= NULL

Shuffle the import_obj initialization above these if statements so that
it is not used uninitialized.

Fixes: d7b2cb380b3a ("drm/i915/gem: Correct the locking and pin pattern for dma-buf (v8)")
Reported-by: Dan Carpenter <[email protected]>
Signed-off-by: Nathan Chancellor <[email protected]>
---
drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c
index ffae7df5e4d7..532c7955b300 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c
@@ -59,13 +59,13 @@ static int igt_dmabuf_import_self(void *arg)
err = PTR_ERR(import);
goto out_dmabuf;
}
+ import_obj = to_intel_bo(import);

if (import != &obj->base) {
pr_err("i915_gem_prime_import created a new object!\n");
err = -EINVAL;
goto out_import;
}
- import_obj = to_intel_bo(import);

i915_gem_object_lock(import_obj, NULL);
err = __i915_gem_object_get_pages(import_obj);
@@ -176,6 +176,7 @@ static int igt_dmabuf_import_same_driver(struct drm_i915_private *i915,
err = PTR_ERR(import);
goto out_dmabuf;
}
+ import_obj = to_intel_bo(import);

if (import == &obj->base) {
pr_err("i915_gem_prime_import reused gem object!\n");
@@ -183,8 +184,6 @@ static int igt_dmabuf_import_same_driver(struct drm_i915_private *i915,
goto out_import;
}

- import_obj = to_intel_bo(import);
-
i915_gem_object_lock(import_obj, NULL);
err = __i915_gem_object_get_pages(import_obj);
if (err) {
--
2.33.0

2021-08-25 10:01:13

by Thomas Hellström

Subject: Re: [PATCH 1/3] drm/i915/selftests: Do not use import_obj uninitialized

On 8/25/21 12:54 AM, Nathan Chancellor wrote:
> Clang warns a couple of times:
>
> drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c:63:6: warning:
> variable 'import_obj' is used uninitialized whenever 'if' condition is
> true [-Wsometimes-uninitialized]
> if (import != &obj->base) {
> ^~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c:80:22: note:
> uninitialized use occurs here
> i915_gem_object_put(import_obj);
> ^~~~~~~~~~
> drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c:63:2: note: remove
> the 'if' if its condition is always false
> if (import != &obj->base) {
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c:38:46: note:
> initialize the variable 'import_obj' to silence this warning
> struct drm_i915_gem_object *obj, *import_obj;
> ^
> = NULL
>
> Shuffle the import_obj initialization above these if statements so that
> it is not used uninitialized.
>
> Fixes: d7b2cb380b3a ("drm/i915/gem: Correct the locking and pin pattern for dma-buf (v8)")
> Reported-by: Dan Carpenter <[email protected]>
> Signed-off-by: Nathan Chancellor <[email protected]>

Patch looks good to me.

Reviewed-by: Thomas Hellström <[email protected]>