Messages in this thread | | | Subject | Re: [PATCH v2] shmem: avoid maybe-uninitialized warning | From | Vlastimil Babka <> | Date | Tue, 25 Oct 2016 10:56:28 +0200 |
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On 10/24/2016 10:57 PM, Arnd Bergmann wrote: > 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 > Acked-by: Michal Hocko <mhocko@suse.com> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
> --- > mm/shmem.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/mm/shmem.c b/mm/shmem.c > index ad7813d73ea7..95c4bb690f98 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -1537,7 +1537,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, > 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 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, > * 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; > > @@ -1835,7 +1834,6 @@ alloc_nohuge: page = shmem_alloc_and_acct_page(gfp, info, sbinfo, > 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); >
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