[Xen-devel] [PATCH] xen-netback: correct return value checks on xenbus_scanf()

["Jan Beulich" <JBeulich@xxxxxxxx>]

Only a positive return value indicates success.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 drivers/net/xen-netback/xenbus.c |   26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

--- 4.7-rc6-xenbus_scanf.orig/drivers/net/xen-netback/xenbus.c
+++ 4.7-rc6-xenbus_scanf/drivers/net/xen-netback/xenbus.c
@@ -741,7 +741,7 @@ static void xen_mcast_ctrl_changed(struc
        int val;
 
        if (xenbus_scanf(XBT_NIL, dev->otherend,
-                        "request-multicast-control", "%d", &val) < 0)
+                        "request-multicast-control", "%d", &val) <= 0)
                val = 0;
        vif->multicast_control = !!val;
 }
@@ -890,7 +890,7 @@ static void connect(struct backend_info
        err = xenbus_scanf(XBT_NIL, dev->otherend,
                           "multi-queue-num-queues",
                           "%u", &requested_num_queues);
-       if (err < 0) {
+       if (err <= 0) {
                requested_num_queues = 1; /* Fall back to single queue */
        } else if (requested_num_queues > xenvif_max_queues) {
                /* buggy or malicious guest */
@@ -1056,7 +1056,7 @@ static int connect_data_rings(struct bac
        if (err < 0) {
                err = xenbus_scanf(XBT_NIL, xspath,
                                   "event-channel", "%u", &tx_evtchn);
-               if (err < 0) {
+               if (err <= 0) {
                        xenbus_dev_fatal(dev, err,
                                         "reading %s/event-channel(-tx/rx)",
                                         xspath);
@@ -1092,10 +1092,10 @@ static int read_xenbus_vif_flags(struct
        err = xenbus_scanf(XBT_NIL, dev->otherend, "request-rx-copy", "%u",
                           &rx_copy);
        if (err == -ENOENT) {
-               err = 0;
+               err = 1;
                rx_copy = 0;
        }
-       if (err < 0) {
+       if (err <= 0) {
                xenbus_dev_fatal(dev, err, "reading %s/request-rx-copy",
                                 dev->otherend);
                return err;
@@ -1104,7 +1104,7 @@ static int read_xenbus_vif_flags(struct
                return -EOPNOTSUPP;
 
        if (xenbus_scanf(XBT_NIL, dev->otherend,
-                        "feature-rx-notify", "%d", &val) < 0)
+                        "feature-rx-notify", "%d", &val) <= 0)
                val = 0;
        if (!val) {
                /* - Reduce drain timeout to poll more frequently for
@@ -1116,7 +1116,7 @@ static int read_xenbus_vif_flags(struct
        }
 
        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg",
-                        "%d", &val) < 0)
+                        "%d", &val) <= 0)
                val = 0;
        vif->can_sg = !!val;
 
@@ -1124,25 +1124,25 @@ static int read_xenbus_vif_flags(struct
        vif->gso_prefix_mask = 0;
 
        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4",
-                        "%d", &val) < 0)
+                        "%d", &val) <= 0)
                val = 0;
        if (val)
                vif->gso_mask |= GSO_BIT(TCPV4);
 
        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4-prefix",
-                        "%d", &val) < 0)
+                        "%d", &val) <= 0)
                val = 0;
        if (val)
                vif->gso_prefix_mask |= GSO_BIT(TCPV4);
 
        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6",
-                        "%d", &val) < 0)
+                        "%d", &val) <= 0)
                val = 0;
        if (val)
                vif->gso_mask |= GSO_BIT(TCPV6);
 
        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6-prefix",
-                        "%d", &val) < 0)
+                        "%d", &val) <= 0)
                val = 0;
        if (val)
                vif->gso_prefix_mask |= GSO_BIT(TCPV6);
@@ -1156,12 +1156,12 @@ static int read_xenbus_vif_flags(struct
        }
 
        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-offload",
-                        "%d", &val) < 0)
+                        "%d", &val) <= 0)
                val = 0;
        vif->ip_csum = !val;
 
        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-ipv6-csum-offload",
-                        "%d", &val) < 0)
+                        "%d", &val) <= 0)
                val = 0;
        vif->ipv6_csum = !!val;
 




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