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From:   Nathan Chancellor <nathan@kernel.org>
To:     Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc:     Jason Ekstrand <jason@jlekstrand.net>,
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        <thomas.hellstrom@linux.intel.com>,
        Matthew Auld <matthew.auld@intel.com>,
        "Michael J. Ruhl" <michael.j.ruhl@intel.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
        llvm@lists.linux.dev, Nathan Chancellor <nathan@kernel.org>,
        Dan Carpenter <dan.carpenter@oracle.com>
Subject: [PATCH 1/3] drm/i915/selftests: Do not use import_obj uninitialized
Date:   Tue, 24 Aug 2021 15:54:25 -0700
Message-Id: <20210824225427.2065517-2-nathan@kernel.org>
In-Reply-To: <20210824225427.2065517-1-nathan@kernel.org>
References: <20210824225427.2065517-1-nathan@kernel.org>
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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 <dan.carpenter@oracle.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 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