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 @@ -1539,7 +1539,7 @@ 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; @@ -1589,7 +1589,6 @@ 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; @@ -1837,7 +1836,6 @@ 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); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
