RE: drivers/vdpa/vdpa.c:296 vdpa_mgmtdev_fill() warn: should '(((1))) << (mdev->id_table[i]->device)' be a 64 bit type?

From: Parav Pandit
Date: Thu Nov 25 2021 - 12:41:37 EST




> From: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Sent: Thursday, November 25, 2021 9:46 PM
>
> On Thu, Nov 25, 2021 at 10:03:28AM +0300, Dan Carpenter wrote:
> > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> master
> > head: 5d9f4cf36721aba199975a9be7863a3ff5cd4b59
> > commit: 33b347503f014ebf76257327cbc7001c6b721956 vdpa: Define vdpa
> > mgmt device, ops and a netlink interface
> > config: i386-randconfig-m021-20211118
> > (https://download.01.org/0day-
> ci/archive/20211125/202111250317.VUsGtdo
> > x-lkp@xxxxxxxxx/config)
> > compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
> >
> > If you fix the issue, kindly add following tag as appropriate
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> >
> > smatch warnings:
> > drivers/vdpa/vdpa.c:296 vdpa_mgmtdev_fill() warn: should '(((1))) << (mdev-
> >id_table[i]->device)' be a 64 bit type?
> >
> > vim +296 drivers/vdpa/vdpa.c
> >
> > 33b347503f014eb Parav Pandit 2021-01-05 280 static int
> vdpa_mgmtdev_fill(const struct vdpa_mgmt_dev *mdev, struct sk_buff *msg,
> > 33b347503f014eb Parav Pandit 2021-01-05 281 u32
> portid, u32 seq, int flags)
> > 33b347503f014eb Parav Pandit 2021-01-05 282 {
> > 33b347503f014eb Parav Pandit 2021-01-05 283 u64
> supported_classes = 0;
> > ^^^^^^^^^^^^^^^^^^^^^
> > This is a u64
> >
> > 33b347503f014eb Parav Pandit 2021-01-05 284 void *hdr;
> > 33b347503f014eb Parav Pandit 2021-01-05 285 int i = 0;
> > 33b347503f014eb Parav Pandit 2021-01-05 286 int err;
> > 33b347503f014eb Parav Pandit 2021-01-05 287
> > 33b347503f014eb Parav Pandit 2021-01-05 288 hdr =
> genlmsg_put(msg, portid, seq, &vdpa_nl_family, flags,
> VDPA_CMD_MGMTDEV_NEW);
> > 33b347503f014eb Parav Pandit 2021-01-05 289 if (!hdr)
> > 33b347503f014eb Parav Pandit 2021-01-05 290 return -
> EMSGSIZE;
> > 33b347503f014eb Parav Pandit 2021-01-05 291 err =
> vdpa_nl_mgmtdev_handle_fill(msg, mdev);
> > 33b347503f014eb Parav Pandit 2021-01-05 292 if (err)
> > 33b347503f014eb Parav Pandit 2021-01-05 293 goto msg_err;
> > 33b347503f014eb Parav Pandit 2021-01-05 294
> > 33b347503f014eb Parav Pandit 2021-01-05 295 while (mdev-
> >id_table[i].device) {
> > 33b347503f014eb Parav Pandit 2021-01-05 @296
> supported_classes |= BIT(mdev->id_table[i].device);
> >
> > Which suggests that this should be BIT_ULL().
> >
> > 33b347503f014eb Parav Pandit 2021-01-05 297 i++;
> > 33b347503f014eb Parav Pandit 2021-01-05 298 }
> > 33b347503f014eb Parav Pandit 2021-01-05 299
> > 33b347503f014eb Parav Pandit 2021-01-05 300 if
> (nla_put_u64_64bit(msg, VDPA_ATTR_MGMTDEV_SUPPORTED_CLASSES,
> > 33b347503f014eb Parav Pandit 2021-01-05 301
> supported_classes, VDPA_ATTR_UNSPEC)) {
> > 33b347503f014eb Parav Pandit 2021-01-05 302 err = -
> EMSGSIZE;
> > 33b347503f014eb Parav Pandit 2021-01-05 303 goto msg_err;
> > 33b347503f014eb Parav Pandit 2021-01-05 304 }
> > 33b347503f014eb Parav Pandit 2021-01-05 305
> > 33b347503f014eb Parav Pandit 2021-01-05 306 genlmsg_end(msg,
> hdr);
> > 33b347503f014eb Parav Pandit 2021-01-05 307 return 0;
> > 33b347503f014eb Parav Pandit 2021-01-05 308 33b347503f014eb Parav
> > Pandit 2021-01-05 309 msg_err:
> > 33b347503f014eb Parav Pandit 2021-01-05 310 genlmsg_cancel(msg,
> hdr);
> > 33b347503f014eb Parav Pandit 2021-01-05 311 return err;
> > 33b347503f014eb Parav Pandit 2021-01-05 312 }
>
>
> Parav? Any patches for this one?

Thanks Dan for reporting.

There are no in kernel drivers today that can register vdpa device with device id > 31.
But I agree that this code should not assume that.
I will shortly supply a patch to fix this warning.