Commit 51889763 authored Jul 16, 2019 by Arnd Bergmann Committed by Alexander Potapenko Aug 30, 2019

UPSTREAM: lib/test_meminit.c: fix -Wmaybe-uninitialized false positive

Upstream commit d3a811617ae6 ("lib/test_meminit.c: fix
-Wmaybe-uninitialized false positive").

The conditional logic is too complicated for the compiler to fully
comprehend:

  lib/test_meminit.c: In function 'test_meminit_init':
  lib/test_meminit.c:236:5: error: 'buf_copy' may be used uninitialized in this function [-Werror=maybe-uninitialized]
       kfree(buf_copy);
       ^~~~~~~~~~~~~~~
  lib/test_meminit.c:201:14: note: 'buf_copy' was declared here

Simplify it by splitting out the non-rcu section.

Link: http://lkml.kernel.org/r/20190617131210.2190280-1-arnd@arndb.de


Fixes: af734ee6ec85 ("lib: introduce test_meminit module")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Change-Id: I810a4b8f115f387c8ffe30937ac1225849520132
Bug: 138435492
Test: Boot cuttlefish with and without
Test:   CONFIG_INIT_ON_ALLOC_DEFAULT_ON/CONFIG_INIT_ON_FREE_DEFAULT_ON
Signed-off-by: Alexander Potapenko <glider@google.com>

parent e7038757

lib/test_meminit.c

+26 −24

Original line number	Diff line number	Diff line
		@@ -208,11 +208,16 @@ static int __init do_kmem_cache_size(size_t size, bool want_ctor,
		/* Check that buf is zeroed, if it must be. */
		fail = check_buf(buf, size, want_ctor, want_rcu, want_zero);
		fill_with_garbage_skip(buf, size, want_ctor ? CTOR_BYTES : 0);

		if (!want_rcu) {
		kmem_cache_free(c, buf);
		continue;
		}

		/*
		* If this is an RCU cache, use a critical section to ensure we
		* can touch objects after they're freed.
		*/
		if (want_rcu) {
		rcu_read_lock();
		/*
		* Copy the buffer to check that it's not wiped on
		@@ -221,9 +226,7 @@ static int __init do_kmem_cache_size(size_t size, bool want_ctor,
		buf_copy = kmalloc(size, GFP_KERNEL);
		if (buf_copy)
		memcpy(buf_copy, buf, size);
		}
		kmem_cache_free(c, buf);
		if (want_rcu) {

		/*
		* Check that \|buf\| is intact after kmem_cache_free().
		* \|want_zero\| is false, because we wrote garbage to
		@@ -237,7 +240,6 @@ static int __init do_kmem_cache_size(size_t size, bool want_ctor,
		}
		rcu_read_unlock();
		}
		}
		kmem_cache_destroy(c);

		*total_failures += fail;