From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id C22176B0253 for ; Tue, 25 Oct 2016 04:56:32 -0400 (EDT) Received: by mail-wm0-f71.google.com with SMTP id 79so2397721wmy.6 for ; Tue, 25 Oct 2016 01:56:32 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id jc5si21069137wjb.204.2016.10.25.01.56.30 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 25 Oct 2016 01:56:31 -0700 (PDT) Subject: Re: [PATCH v2] shmem: avoid maybe-uninitialized warning References: <20161024205725.786455-1-arnd@arndb.de> From: Vlastimil Babka Message-ID: <627676b7-a210-cb76-f470-d86ce452a658@suse.cz> Date: Tue, 25 Oct 2016 10:56:28 +0200 MIME-Version: 1.0 In-Reply-To: <20161024205725.786455-1-arnd@arndb.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Arnd Bergmann , Hugh Dickins Cc: Andrew Morton , Al Viro , "Kirill A. Shutemov" , Michal Hocko , Andreas Gruenbacher , linux-mm@kvack.org, linux-kernel@vger.kernel.org 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 a??shmem_getpage_gfpa??: > include/linux/spinlock.h:332:21: error: a??infoa?? 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 > Signed-off-by: Arnd Bergmann Acked-by: Vlastimil Babka > --- > 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); > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org