ethtool: Add direct access to ops->get_sset_count

This patch is an alternative approach for accessing string
counts, vs. the drvinfo indirect approach.  This way the drvinfo
space doesn't run out, and we don't break ABI later.
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/ethtool.h

@@ -253,6 +253,17 @@ struct ethtool_gstrings {
 	__u8	data[0];
 };
 
+struct ethtool_sset_info {
+	__u32	cmd;		/* ETHTOOL_GSSET_INFO */
+	__u32	reserved;
+	__u64	sset_mask;	/* input: each bit selects an sset to query */
+				/* output: each bit a returned sset */
+	__u32	data[0];	/* ETH_SS_xxx count, in order, based on bits
+				   in sset_mask.  One bit implies one
+				   __u32, two bits implies two
+				   __u32's, etc. */
+};
+
 enum ethtool_test_flags {
 	ETH_TEST_FL_OFFLINE	= (1 << 0),	/* online / offline */
 	ETH_TEST_FL_FAILED	= (1 << 1),	/* test passed / failed */
@@ -606,9 +617,9 @@ struct ethtool_ops {
 #define	ETHTOOL_SRXCLSRLINS	0x00000032 /* Insert RX classification rule */
 #define	ETHTOOL_FLASHDEV	0x00000033 /* Flash firmware to device */
 #define	ETHTOOL_RESET		0x00000034 /* Reset hardware */
-
-#define ETHTOOL_SRXNTUPLE	0x00000035 /* Add an n-tuple filter to device */
-#define ETHTOOL_GRXNTUPLE	0x00000036 /* Get n-tuple filters from device */
+#define	ETHTOOL_SRXNTUPLE	0x00000035 /* Add an n-tuple filter to device */
+#define	ETHTOOL_GRXNTUPLE	0x00000036 /* Get n-tuple filters from device */
+#define	ETHTOOL_GSSET_INFO	0x00000037 /* Get string set info */
 
 /* compatibility with older code */
 #define SPARC_ETH_GSET		ETHTOOL_GSET

net/core/ethtool.c

@@ -214,6 +214,10 @@ static noinline int ethtool_get_drvinfo(struct net_device *dev, void __user *use
 	info.cmd = ETHTOOL_GDRVINFO;
 	ops->get_drvinfo(dev, &info);
 
+	/*
+	 * this method of obtaining string set info is deprecated;
+	 * consider using ETHTOOL_GSSET_INFO instead
+	 */
 	if (ops->get_sset_count) {
 		int rc;
 
@@ -237,6 +241,71 @@ static noinline int ethtool_get_drvinfo(struct net_device *dev, void __user *use
 	return 0;
 }
 
+/*
+ * noinline attribute so that gcc doesnt use too much stack in dev_ethtool()
+ */
+static noinline int ethtool_get_sset_info(struct net_device *dev,
+                                          void __user *useraddr)
+{
+	struct ethtool_sset_info info;
+	const struct ethtool_ops *ops = dev->ethtool_ops;
+	u64 sset_mask;
+	int i, idx = 0, n_bits = 0, ret, rc;
+	u32 *info_buf = NULL;
+
+	if (!ops->get_sset_count)
+		return -EOPNOTSUPP;
+
+	if (copy_from_user(&info, useraddr, sizeof(info)))
+		return -EFAULT;
+
+	/* store copy of mask, because we zero struct later on */
+	sset_mask = info.sset_mask;
+	if (!sset_mask)
+		return 0;
+
+	/* calculate size of return buffer */
+	for (i = 0; i < 64; i++)
+		if (sset_mask & (1ULL << i))
+			n_bits++;
+
+	memset(&info, 0, sizeof(info));
+	info.cmd = ETHTOOL_GSSET_INFO;
+
+	info_buf = kzalloc(n_bits * sizeof(u32), GFP_USER);
+	if (!info_buf)
+		return -ENOMEM;
+
+	/*
+	 * fill return buffer based on input bitmask and successful
+	 * get_sset_count return
+	 */
+	for (i = 0; i < 64; i++) {
+		if (!(sset_mask & (1ULL << i)))
+			continue;
+
+		rc = ops->get_sset_count(dev, i);
+		if (rc >= 0) {
+			info.sset_mask |= (1ULL << i);
+			info_buf[idx++] = rc;
+		}
+	}
+
+	ret = -EFAULT;
+	if (copy_to_user(useraddr, &info, sizeof(info)))
+		goto out;
+
+	useraddr += offsetof(struct ethtool_sset_info, data);
+	if (copy_to_user(useraddr, info_buf, idx * sizeof(u32)))
+		goto out;
+
+	ret = 0;
+
+out:
+	kfree(info_buf);
+	return ret;
+}
+
 /*
  * noinline attribute so that gcc doesnt use too much stack in dev_ethtool()
  */
@@ -1471,6 +1540,9 @@ int dev_ethtool(struct net *net, struct ifreq *ifr)
 	case ETHTOOL_GRXNTUPLE:
 		rc = ethtool_get_rx_ntuple(dev, useraddr);
 		break;
+	case ETHTOOL_GSSET_INFO:
+		rc = ethtool_get_sset_info(dev, useraddr);
+		break;
 	default:
 		rc = -EOPNOTSUPP;
 	}