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From:   "Xia, Hui" <hui.xia@intel.com>
To:     Vivek Goyal <vgoyal@redhat.com>, lkp <lkp@intel.com>
CC:     Stefan Hajnoczi <stefanha@redhat.com>,
        "kbuild-all@lists.01.org" <kbuild-all@lists.01.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Miklos Szeredi <mszeredi@redhat.com>
Subject: RE: [kbuild-all] Re: fs/fuse/virtio_fs.c:1009:6: warning: Variable
 'err' is reassigned a value before the old one has been used.
Thread-Topic: [kbuild-all] Re: fs/fuse/virtio_fs.c:1009:6: warning: Variable
 'err' is reassigned a value before the old one has been used.
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Date:   Mon, 10 Aug 2020 09:24:48 +0000
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 <20200806174049.GE367847@redhat.com>
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>-----Original Message-----
>From: Vivek Goyal <vgoyal@redhat.com>
>Sent: 2020=1B$BG/=1B(B8=1B$B7n=1B(B7=1B$BF|=1B(B 1:41
>To: kernel test robot <lkp@intel.com>
>Cc: Stefan Hajnoczi <stefanha@redhat.com>; kbuild-all@lists.01.org; linux-
>kernel@vger.kernel.org; Miklos Szeredi <mszeredi@redhat.com>
>Subject: [kbuild-all] Re: fs/fuse/virtio_fs.c:1009:6: warning: Variable 'e=
rr' is
>reassigned a value before the old one has been used.
>
>On Thu, Aug 06, 2020 at 02:04:18PM +0800, kernel test robot wrote:
>> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.g=
it master
>> head:   fffe3ae0ee84e25d2befe2ae59bc32aa2b6bc77b
>> commit: a62a8ef9d97da23762a588592c8b8eb50a8deb6a virtio-fs: add virtiofs
>filesystem
>> date:   11 months ago
>> compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
>>
>> If you fix the issue, kindly add following tag as appropriate
>> Reported-by: kernel test robot <lkp@intel.com>
>>
>>
>> cppcheck warnings: (new ones prefixed by >>)
>>
>> >> fs/fuse/virtio_fs.c:1009:6: warning: Variable 'err' is reassigned a
>> >> value before the old one has been used. [redundantAssignment]
>>     err =3D -ENOMEM;
>>         ^
>>    fs/fuse/virtio_fs.c:1003:6: note: Variable 'err' is reassigned a valu=
e before the
>old one has been used.
>>     err =3D -EINVAL;
>>         ^
>>    fs/fuse/virtio_fs.c:1009:6: note: Variable 'err' is reassigned a valu=
e before the
>old one has been used.
>>     err =3D -ENOMEM;
>>         ^
>>    fs/fuse/virtio_fs.c:1020:6: warning: Variable 'err' is reassigned a v=
alue before
>the old one has been used. [redundantAssignment]
>>     err =3D fuse_fill_super_common(sb, &ctx);
>>         ^
>>    fs/fuse/virtio_fs.c:1009:6: note: Variable 'err' is reassigned a valu=
e before the
>old one has been used.
>>     err =3D -ENOMEM;
>
>Not sure why this is a warning. Previous value is not going to be used any=
more. If
>it were to be used, we would have taken "goto err" path, and return err. V=
ery fact
>that we did not take that path means we are not going to use previous valu=
e of
>err, hence it is ok to override it.
>
>IOW, this seems like a false warning from compiler. This pattern has been =
used in
>fuse and overlayfs code all over the place.

Thanks, Vivek. Please ignore this report.
We will double check this type of warning before send report in future. Sor=
ry for inconvenient.

Thanks,
Hui

>
>Thanks
>Vivek
>
>>         ^
>>    fs/fuse/virtio_fs.c:1020:6: note: Variable 'err' is reassigned a valu=
e before the
>old one has been used.
>>     err =3D fuse_fill_super_common(sb, &ctx);
>>         ^
>>
>> vim +/err +1009 fs/fuse/virtio_fs.c
>>
>>    979
>>    980	static int virtio_fs_fill_super(struct super_block *sb)
>>    981	{
>>    982		struct fuse_conn *fc =3D get_fuse_conn_super(sb);
>>    983		struct virtio_fs *fs =3D fc->iq.priv;
>>    984		unsigned int i;
>>    985		int err;
>>    986		struct fuse_fs_context ctx =3D {
>>    987			.rootmode =3D S_IFDIR,
>>    988			.default_permissions =3D 1,
>>    989			.allow_other =3D 1,
>>    990			.max_read =3D UINT_MAX,
>>    991			.blksize =3D 512,
>>    992			.destroy =3D true,
>>    993			.no_control =3D true,
>>    994			.no_force_umount =3D true,
>>    995		};
>>    996
>>    997		mutex_lock(&virtio_fs_mutex);
>>    998
>>    999		/* After holding mutex, make sure virtiofs device is still there=
.
>>   1000		 * Though we are holding a reference to it, drive ->remove might
>>   1001		 * still have cleaned up virtual queues. In that case bail out.
>>   1002		 */
>>   1003		err =3D -EINVAL;
>>   1004		if (list_empty(&fs->list)) {
>>   1005			pr_info("virtio-fs: tag <%s> not found\n", fs->tag);
>>   1006			goto err;
>>   1007		}
>>   1008
>> > 1009		err =3D -ENOMEM;
>>   1010		/* Allocate fuse_dev for hiprio and notification queues */
>>   1011		for (i =3D 0; i < VQ_REQUEST; i++) {
>>   1012			struct virtio_fs_vq *fsvq =3D &fs->vqs[i];
>>   1013
>>   1014			fsvq->fud =3D fuse_dev_alloc();
>>   1015			if (!fsvq->fud)
>>   1016				goto err_free_fuse_devs;
>>   1017		}
>>   1018
>>   1019		ctx.fudptr =3D (void **)&fs->vqs[VQ_REQUEST].fud;
>>   1020		err =3D fuse_fill_super_common(sb, &ctx);
>>   1021		if (err < 0)
>>   1022			goto err_free_fuse_devs;
>>   1023
>>   1024		fc =3D fs->vqs[VQ_REQUEST].fud->fc;
>>   1025
>>   1026		for (i =3D 0; i < fs->nvqs; i++) {
>>   1027			struct virtio_fs_vq *fsvq =3D &fs->vqs[i];
>>   1028
>>   1029			if (i =3D=3D VQ_REQUEST)
>>   1030				continue; /* already initialized */
>>   1031			fuse_dev_install(fsvq->fud, fc);
>>   1032		}
>>   1033
>>   1034		/* Previous unmount will stop all queues. Start these again */
>>   1035		virtio_fs_start_all_queues(fs);
>>   1036		fuse_send_init(fc);
>>   1037		mutex_unlock(&virtio_fs_mutex);
>>   1038		return 0;
>>   1039
>>   1040	err_free_fuse_devs:
>>   1041		virtio_fs_free_devs(fs);
>>   1042	err:
>>   1043		mutex_unlock(&virtio_fs_mutex);
>>   1044		return err;
>>   1045	}
>>   1046
>>
>> ---
>> 0-DAY CI Kernel Test Service, Intel Corporation
>> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
>>
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