kcsan: test: Initialize dummy variable

[ Upstream commit 9872916ad1a1a5e7d089e05166c85dbd65e5b0e8 ]

Newer compiler versions rightfully point out:

 kernel/kcsan/kcsan_test.c:591:41: error: variable 'dummy' is
 uninitialized when passed as a const pointer argument here
 [-Werror,-Wuninitialized-const-pointer]
   591 |         KCSAN_EXPECT_READ_BARRIER(atomic_read(&dummy), false);
       |                                                ^~~~~
 1 error generated.

Although this particular test does not care about the value stored in
the dummy atomic variable, let's silence the warning.

Link: https://lkml.kernel.org/r/CA+G9fYu8JY=k-r0hnBRSkQQrFJ1Bz+ShdXNwC1TNeMt0eXaxeA@mail.gmail.com
Fixes: 8bc32b3 ("kcsan: test: Add test cases for memory barrier instrumentation")
Reported-by: Linux Kernel Functional Testing <[email protected]>
Reviewed-by: Alexander Potapenko <[email protected]>
Signed-off-by: Marco Elver <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
(cherry picked from commit cdb509f59aaf0624bb6113cbb022968e2e1eda5a)

Author: melver

kernel/kcsan/kcsan_test.c

@@ -530,7 +530,7 @@ static void test_barrier_nothreads(struct kunit *test)
 	struct kcsan_scoped_access *reorder_access = NULL;
 #endif
 	arch_spinlock_t arch_spinlock = __ARCH_SPIN_LOCK_UNLOCKED;
-	atomic_t dummy;
+	atomic_t dummy = ATOMIC_INIT(0);
 
 	KCSAN_TEST_REQUIRES(test, reorder_access != NULL);
 	KCSAN_TEST_REQUIRES(test, IS_ENABLED(CONFIG_SMP));