Re: [akpm-mm:mm-unstable 36/78] test_memcontrol.c:201:6: warning: variable 'fd4_closed' is used uninitialized whenever 'if' condition is true

[Philip Li <philip.li@intel.com>]

On Sun, Jul 28, 2024 at 01:18:24PM -0700, Andrew Morton wrote:
> On Sun, 28 Jul 2024 11:58:47 +0800 kernel test robot <lkp@intel.com> wrote:
> 
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable
> > head:   b39b3892d20a337489c55806f91af581474f3943
> > commit: f2db5cca8182337f4ad485ebfd532b1a2d1c223a [36/78] mm, memcg: cg2 memory{.swap,}.peak write tests
> > :::::: branch date: 2 days ago
> > :::::: commit date: 3 days ago
> > compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
> > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240727/202407272301.bBC2CidR-lkp@intel.com/reproduce)
> > 
> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > the same patch/commit), kindly add following tags
> > | Reported-by: kernel test robot <lkp@intel.com>
> > | Closes: https://lore.kernel.org/r/202407272301.bBC2CidR-lkp@intel.com/
> > 
> > All warnings (new ones prefixed by >>):
> > 
> > >> test_memcontrol.c:201:6: warning: variable 'fd4_closed' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
> 
> um,
> 
> 	bool fd2_closed = false, fd3_closed = false, fd4_closed = false;
> 
> fd4_closed cannot possibly be used uninitialized?

One possible flow is early peak_fd fails to open and go to cleanup, then
in cleanup side, the variable like fd4_closed is directly used.

+       if (peak_fd == -1)
+               goto cleanup;
+
+       bool fd2_closed = false, fd3_closed = false, fd4_closed = false;
+       int peak_fd2 = cg_open(memcg, "memory.peak", O_RDWR | O_APPEND | O_CLOEXEC);
+
 ...

 cleanup:
+       close(peak_fd);
+       if (!fd2_closed)
+               close(peak_fd2);
+       if (!fd3_closed)
+               close(peak_fd3);
+       if (!fd4_closed)
+               close(peak_fd4);

>