The patch titled
Subject: shmem: avoid maybe-uninitialized warning
has been added to the -mm tree. Its filename is
shmem-avoid-maybe-uninitialized-warning.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/shmem-avoid-maybe-uninitialized-warning.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/shmem-avoid-maybe-uninitialized-warning.patch
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------------------------------------------------------
From: Arnd Bergmann <arnd@xxxxxxxx>
Subject: shmem: avoid maybe-uninitialized warning
After enabling -Wmaybe-uninitialized warnings, we get a false-postive
warning for shmem:
mm/shmem.c: In function `shmem_getpage_gfp':
include/linux/spinlock.h:332:21: error: `info' may be used uninitialized in this function [-Werror=maybe-uninitialized]
This can be easily avoided, since the correct 'info' pointer is known at
the time we first enter the function, so we can simply move the
initialization up. Moving it before the first label avoids the warning
and lets us remove two later initializations.
Note that the function is so hard to read that it not only confuses the
compiler, but also most readers and without this patch it could\ easily
break if one of the 'goto's changed.
Link: https://www.spinics.net/lists/kernel/msg2368133.html
Link: http://lkml.kernel.org/r/20161024205725.786455-1-arnd@xxxxxxxx
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/shmem.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff -puN mm/shmem.c~shmem-avoid-maybe-uninitialized-warning mm/shmem.c
--- a/mm/shmem.c~shmem-avoid-maybe-uninitialized-warning
+++ a/mm/shmem.c
@@ -1537,7 +1537,7 @@ static int shmem_getpage_gfp(struct inod
struct mm_struct *fault_mm, int *fault_type)
{
struct address_space *mapping = inode->i_mapping;
- struct shmem_inode_info *info;
+ struct shmem_inode_info *info = SHMEM_I(inode);
struct shmem_sb_info *sbinfo;
struct mm_struct *charge_mm;
struct mem_cgroup *memcg;
@@ -1587,7 +1587,6 @@ repeat:
* Fast cache lookup did not find it:
* bring it back from swap or allocate.
*/
- info = SHMEM_I(inode);
sbinfo = SHMEM_SB(inode->i_sb);
charge_mm = fault_mm ? : current->mm;
@@ -1840,7 +1839,6 @@ unlock:
put_page(page);
}
if (error == -ENOSPC && !once++) {
- info = SHMEM_I(inode);
spin_lock_irq(&info->lock);
shmem_recalc_inode(inode);
spin_unlock_irq(&info->lock);
_
Patches currently in -mm which might be from arnd@xxxxxxxx are
slub-avoid-false-postive-warning.patch
shmem-avoid-maybe-uninitialized-warning.patch
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