ethtool: Add n-tuple string length to drvinfo and return it

The drvinfo struct should include the number of strings that
get_rx_ntuple will return.  It will be variable if an underlying
driver implements its own get_rx_ntuple routine, so userspace
needs to know how much data is coming.
Signed-off-by: NPeter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/ethtool.h

@@ -63,6 +63,7 @@ struct ethtool_drvinfo {
 	char	reserved2[12];
 	__u32	n_priv_flags;	/* number of flags valid in ETHTOOL_GPFLAGS */
 	__u32	n_stats;	/* number of u64's from ETHTOOL_GSTATS */
+	__u32	n_ntuples;	/* number of n-tuple filters from GSTRINGS */
 	__u32	testinfo_len;
 	__u32	eedump_len;	/* Size of data from ETHTOOL_GEEPROM (bytes) */
 	__u32	regdump_len;	/* Size of data from ETHTOOL_GREGS (bytes) */

net/core/ethtool.c

@@ -224,6 +224,9 @@ static noinline int ethtool_get_drvinfo(struct net_device *dev, void __user *use
 		rc = ops->get_sset_count(dev, ETH_SS_PRIV_FLAGS);
 		if (rc >= 0)
 			info.n_priv_flags = rc;
+		rc = ops->get_sset_count(dev, ETH_SS_NTUPLE_FILTERS);
+		if (rc >= 0)
+			info.n_ntuples = rc;
 	}
 	if (ops->get_regs_len)
 		info.regdump_len = ops->get_regs_len(dev);