ethtool: Call ethtool's get/set_settings callbacks with cleaned data

This makes sure that when a driver calls the ethtool's
get/set_settings() callback of another driver, the data passed to it
is clean. This guarantees that speed_hi will be zeroed correctly if
the called callback doesn't explicitely set it: we are sure we don't
get a corrupted speed from the underlying driver. We also take care of
setting the cmd field appropriately (ETHTOOL_GSET/SSET).

This applies to dev_ethtool_get_settings(), which now makes sure it
sets up that ethtool command parameter correctly before passing it to
drivers. This also means that whoever calls dev_ethtool_get_settings()
does not have to clean the ethtool command parameter. This function
also becomes an exported symbol instead of an inline.

All drivers visible to make allyesconfig under x86_64 have been
updated.

Signed-off-by: David Decotigny <decot@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 34 insertions, 14 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 7db99b52679f..e95dc30110eb 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4496,6 +4496,30 @@ void dev_set_rx_mode(struct net_device *dev)
 }
 
 /**
+ *      dev_ethtool_get_settings - call device's ethtool_ops::get_settings()
+ *      @dev: device
+ *      @cmd: memory area for ethtool_ops::get_settings() result
+ *
+ *      The cmd arg is initialized properly (cleared and
+ *      ethtool_cmd::cmd field set to ETHTOOL_GSET).
+ *
+ *      Return device's ethtool_ops::get_settings() result value or
+ *      -EOPNOTSUPP when device doesn't expose
+ *      ethtool_ops::get_settings() operation.
+ */
+int dev_ethtool_get_settings(struct net_device *dev,
+                             struct ethtool_cmd *cmd)
+{
+        if (!dev->ethtool_ops || !dev->ethtool_ops->get_settings)
+                return -EOPNOTSUPP;
+
+        memset(cmd, 0, sizeof(struct ethtool_cmd));
+        cmd->cmd = ETHTOOL_GSET;
+        return dev->ethtool_ops->get_settings(dev, cmd);
+}
+EXPORT_SYMBOL(dev_ethtool_get_settings);
+
+/**
  *      dev_get_flags - get flags reported to userspace
  *      @dev: device
  *
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 5ceb257e860c..381813eae46c 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -28,6 +28,7 @@
 static const char fmt_hex[] = "%#x\n";
 static const char fmt_long_hex[] = "%#lx\n";
 static const char fmt_dec[] = "%d\n";
+static const char fmt_udec[] = "%u\n";
 static const char fmt_ulong[] = "%lu\n";
 static const char fmt_u64[] = "%llu\n";
 
@@ -145,13 +146,10 @@ static ssize_t show_speed(struct device *dev,
         if (!rtnl_trylock())
                 return restart_syscall();
 
-        if (netif_running(netdev) &&
-            netdev->ethtool_ops &&
-            netdev->ethtool_ops->get_settings) {
-                struct ethtool_cmd cmd = { ETHTOOL_GSET };
-
-                if (!netdev->ethtool_ops->get_settings(netdev, &cmd))
-                        ret = sprintf(buf, fmt_dec, ethtool_cmd_speed(&cmd));
+        if (netif_running(netdev)) {
+                struct ethtool_cmd cmd;
+                if (!dev_ethtool_get_settings(netdev, &cmd))
+                        ret = sprintf(buf, fmt_udec, ethtool_cmd_speed(&cmd));
         }
         rtnl_unlock();
         return ret;
@@ -166,13 +164,11 @@ static ssize_t show_duplex(struct device *dev,
         if (!rtnl_trylock())
                 return restart_syscall();
 
-        if (netif_running(netdev) &&
-            netdev->ethtool_ops &&
-            netdev->ethtool_ops->get_settings) {
-                struct ethtool_cmd cmd = { ETHTOOL_GSET };
-
-                if (!netdev->ethtool_ops->get_settings(netdev, &cmd))
-                        ret = sprintf(buf, "%s\n", cmd.duplex ? "full" : "half");
+        if (netif_running(netdev)) {
+                struct ethtool_cmd cmd;
+                if (!dev_ethtool_get_settings(netdev, &cmd))
+                        ret = sprintf(buf, "%s\n",
+                                      cmd.duplex ? "full" : "half");
         }
         rtnl_unlock();
         return ret;