> -----Original Message-----
> From: Juergen Gross [mailto:jgr...@suse.com]
> Sent: 31 October 2016 16:48
> To: linux-ker...@vger.kernel.org; xen-devel@lists.xen.org
> Cc: David Vrabel <david.vra...@citrix.com>; boris.ostrov...@oracle.com;
> Juergen Gross <jgr...@suse.com>; Wei Liu <wei.l...@citrix.com>; Paul
> Durrant <paul.durr...@citrix.com>; net...@vger.kernel.org
> Subject: [PATCH 06/12] xen: make use of xenbus_read_unsigned() in xen-
> netback
>
> Use xenbus_read_unsigned() instead of xenbus_scanf() when possible.
> This requires to change the type of some reads from int to unsigned,
> but these cases have been wrong before: negative values are not allowed
> for the modified cases.
>
> Cc: wei.l...@citrix.com
> Cc: paul.durr...@citrix.com
Reviewed-by: Paul Durrant <paul.durr...@citrix.com>
> Cc: net...@vger.kernel.org
>
> Signed-off-by: Juergen Gross <jgr...@suse.com>
> ---
> drivers/net/xen-netback/xenbus.c | 50 +++++++++++---------------------------
> --
> 1 file changed, 14 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-
> netback/xenbus.c
> index 8674e18..7356e00 100644
> --- a/drivers/net/xen-netback/xenbus.c
> +++ b/drivers/net/xen-netback/xenbus.c
> @@ -785,12 +785,9 @@ static void xen_mcast_ctrl_changed(struct
> xenbus_watch *watch,
> struct xenvif *vif = container_of(watch, struct xenvif,
> mcast_ctrl_watch);
> struct xenbus_device *dev = xenvif_to_xenbus_device(vif);
> - int val;
>
> - if (xenbus_scanf(XBT_NIL, dev->otherend,
> - "request-multicast-control", "%d", &val) < 0)
> - val = 0;
> - vif->multicast_control = !!val;
> + vif->multicast_control = !!xenbus_read_unsigned(dev->otherend,
> + "request-multicast-control", 0);
> }
>
> static int xen_register_mcast_ctrl_watch(struct xenbus_device *dev,
> @@ -934,12 +931,9 @@ static void connect(struct backend_info *be)
> /* Check whether the frontend requested multiple queues
> * and read the number requested.
> */
> - err = xenbus_scanf(XBT_NIL, dev->otherend,
> - "multi-queue-num-queues",
> - "%u", &requested_num_queues);
> - if (err < 0) {
> - requested_num_queues = 1; /* Fall back to single queue */
> - } else if (requested_num_queues > xenvif_max_queues) {
> + requested_num_queues = xenbus_read_unsigned(dev->otherend,
> + "multi-queue-num-queues", 1);
> + if (requested_num_queues > xenvif_max_queues) {
> /* buggy or malicious guest */
> xenbus_dev_fatal(dev, err,
> "guest requested %u queues, exceeding the
> maximum of %u.",
> @@ -1134,7 +1128,7 @@ static int read_xenbus_vif_flags(struct
> backend_info *be)
> struct xenvif *vif = be->vif;
> struct xenbus_device *dev = be->dev;
> unsigned int rx_copy;
> - int err, val;
> + int err;
>
> err = xenbus_scanf(XBT_NIL, dev->otherend, "request-rx-copy",
> "%u",
> &rx_copy);
> @@ -1150,10 +1144,7 @@ static int read_xenbus_vif_flags(struct
> backend_info *be)
> if (!rx_copy)
> return -EOPNOTSUPP;
>
> - if (xenbus_scanf(XBT_NIL, dev->otherend,
> - "feature-rx-notify", "%d", &val) < 0)
> - val = 0;
> - if (!val) {
> + if (!xenbus_read_unsigned(dev->otherend, "feature-rx-notify", 0)) {
> /* - Reduce drain timeout to poll more frequently for
> * Rx requests.
> * - Disable Rx stall detection.
> @@ -1162,34 +1153,21 @@ static int read_xenbus_vif_flags(struct
> backend_info *be)
> be->vif->stall_timeout = 0;
> }
>
> - if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg",
> - "%d", &val) < 0)
> - val = 0;
> - vif->can_sg = !!val;
> + vif->can_sg = !!xenbus_read_unsigned(dev->otherend, "feature-
> sg", 0);
>
> vif->gso_mask = 0;
>
> - if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4",
> - "%d", &val) < 0)
> - val = 0;
> - if (val)
> + if (xenbus_read_unsigned(dev->otherend, "feature-gso-tcpv4", 0))
> vif->gso_mask |= GSO_BIT(TCPV4);
>
> - if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6",
> - "%d", &val) < 0)
> - val = 0;
> - if (val)
> + if (xenbus_read_unsigned(dev->otherend, "feature-gso-tcpv6", 0))
> vif->gso_mask |= GSO_BIT(TCPV6);
>
> - if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-
> offload",
> - "%d", &val) < 0)
> - val = 0;
> - vif->ip_csum = !val;
> + vif->ip_csum = !xenbus_read_unsigned(dev->otherend,
> + "feature-no-csum-offload", 0);
>
> - if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-ipv6-csum-
> offload",
> - "%d", &val) < 0)
> - val = 0;
> - vif->ipv6_csum = !!val;
> + vif->ipv6_csum = !!xenbus_read_unsigned(dev->otherend,
> + "feature-ipv6-csum-offload",
> 0);
>
> return 0;
> }
> --
> 2.6.6
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