Re: [PATCH -mm] mm/shmem.c: ret can be used uninitialized

Andrew Morton
2008-06-12T01:29:59Z

On Wed, 11 Jun 2008 14:37:29 -0500 "Serge E. Hallyn" <serue@us.ibm.com> wrote:

> >From 6c4eb2ce2849308c4a745ec1f93001e5064a469c Mon Sep 17 00:00:00 2001
> From: Serge Hallyn <serge@us.ibm.com>
> Date: Wed, 11 Jun 2008 11:20:28 -0500
> Subject: [PATCH -mm] mm/shmem.c: ret can be used uninitialized
>
> Make sure ret is defined before check at line 1408.
>
> Signed-off-by: Serge Hallyn <serge@us.ibm.com>
> ---
> mm/shmem.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/mm/shmem.c b/mm/shmem.c
> index ad24be7..b326ff2 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1365,7 +1365,7 @@ repeat:
> }
>
> if (!filepage) {
> - int ret;
> + int ret = 0;
>
> spin_unlock(&info->lock);
> filepage = shmem_alloc_page(gfp, info, idx);

Well yes. But it adds more text and uncommentedly adds an unnecessary
initialisation.

With a wee bit of thought we can _reduce_ the amount of text and not
add unnecessary stuff?

--- a/mm/shmem.c~memcg-remove-refcnt-from-page_cgroup-fix-2
+++ a/mm/shmem.c
@@ -1396,7 +1396,8 @@ repeat:
swap = *entry;
shmem_swp_unmap(entry);
}
- if (error || swap.val)
+ ret = error || swap.val;
+ if (ret)
mem_cgroup_uncharge_cache_page(filepage);
else
ret = add_to_page_cache_lru(filepage, mapping,
@@ -1405,7 +1406,7 @@ repeat:
* At add_to_page_cache_lru() failure, uncharge will
* be done automatically.
*/
- if (error || swap.val || ret) {
+ if (ret) {
spin_unlock(&info->lock);
page_cache_release(filepage);
shmem_unacct_blocks(info->flags, 1);
_