[PATCH net-next v2 14/15] ethtool: set device channel counts with CHANNELS_SET request

From: Michal Kubecek
Date: Thu Mar 12 2020 - 16:08:49 EST

Implement CHANNELS_SET netlink request to set channel counts of a network
device. These are traditionally set with ETHTOOL_SCHANNELS ioctl request.

Like the ioctl implementation, the generic ethtool code checks if supplied
values do not exceed driver defined limits; if they do, first offending
attribute is reported using extack. Checks preventing removing channels
used for RX indirection table or zerocopy AF_XDP socket are also
implemented.

Move ethtool_get_max_rxfh_channel() helper into common.c so that it can be
used by both ioctl and netlink code.

v2:
- fix netdev reference leak in error path (found by Jakub Kicinsky)

Signed-off-by: Michal Kubecek <mkubecek@xxxxxxx>
---
Documentation/networking/ethtool-netlink.rst | 23 +++-
include/uapi/linux/ethtool_netlink.h | 1 +
net/ethtool/channels.c | 116 +++++++++++++++++++
net/ethtool/common.c | 31 +++++
net/ethtool/common.h | 1 +
net/ethtool/ioctl.c | 31 -----
net/ethtool/netlink.c | 5 +
net/ethtool/netlink.h | 1 +
8 files changed, 177 insertions(+), 32 deletions(-)

diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst
index decbbddfd8be..7df7476cf310 100644
--- a/Documentation/networking/ethtool-netlink.rst
+++ b/Documentation/networking/ethtool-netlink.rst
@@ -196,6 +196,7 @@ Userspace to kernel:
``ETHTOOL_MSG_RINGS_GET`` get ring sizes
``ETHTOOL_MSG_RINGS_SET`` set ring sizes
``ETHTOOL_MSG_CHANNELS_GET`` get channel counts
+ ``ETHTOOL_MSG_CHANNELS_SET`` set channel counts
===================================== ================================

Kernel to userspace:
@@ -723,6 +724,26 @@ Kernel response contents:
===================================== ====== ==========================


+CHANNELS_SET
+============
+
+Sets channel counts like ``ETHTOOL_SCHANNELS`` ioctl request.
+
+Request contents:
+
+ ===================================== ====== ==========================
+ ``ETHTOOL_A_CHANNELS_HEADER`` nested request header
+ ``ETHTOOL_A_CHANNELS_RX_COUNT`` u32 receive channel count
+ ``ETHTOOL_A_CHANNELS_TX_COUNT`` u32 transmit channel count
+ ``ETHTOOL_A_CHANNELS_OTHER_COUNT`` u32 other channel count
+ ``ETHTOOL_A_CHANNELS_COMBINED_COUNT`` u32 combined channel count
+ ===================================== ====== ==========================
+
+Kernel checks that requested channel counts do not exceed limits reported by
+driver. Driver may impose additional constraints and may not suspport all
+attributes.
+
+
Request translation
===================

@@ -794,7 +815,7 @@ have their netlink replacement yet.
``ETHTOOL_GFEATURES`` ``ETHTOOL_MSG_FEATURES_GET``
``ETHTOOL_SFEATURES`` ``ETHTOOL_MSG_FEATURES_SET``
``ETHTOOL_GCHANNELS`` ``ETHTOOL_MSG_CHANNELS_GET``
- ``ETHTOOL_SCHANNELS`` n/a
+ ``ETHTOOL_SCHANNELS`` ``ETHTOOL_MSG_CHANNELS_SET``
``ETHTOOL_SET_DUMP`` n/a
``ETHTOOL_GET_DUMP_FLAG`` n/a
``ETHTOOL_GET_DUMP_DATA`` n/a
diff --git a/include/uapi/linux/ethtool_netlink.h b/include/uapi/linux/ethtool_netlink.h
index 2270eb115eca..f1384a8f3534 100644
--- a/include/uapi/linux/ethtool_netlink.h
+++ b/include/uapi/linux/ethtool_netlink.h
@@ -31,6 +31,7 @@ enum {
ETHTOOL_MSG_RINGS_GET,
ETHTOOL_MSG_RINGS_SET,
ETHTOOL_MSG_CHANNELS_GET,
+ ETHTOOL_MSG_CHANNELS_SET,

/* add new constants above here */
__ETHTOOL_MSG_USER_CNT,
diff --git a/net/ethtool/channels.c b/net/ethtool/channels.c
index 500dd5ad250b..ee232c11acae 100644
--- a/net/ethtool/channels.c
+++ b/net/ethtool/channels.c
@@ -1,5 +1,7 @@
// SPDX-License-Identifier: GPL-2.0-only

+#include <net/xdp_sock.h>
+
#include "netlink.h"
#include "common.h"

@@ -106,3 +108,117 @@ const struct ethnl_request_ops ethnl_channels_request_ops = {
.reply_size = channels_reply_size,
.fill_reply = channels_fill_reply,
};
+
+/* CHANNELS_SET */
+
+static const struct nla_policy
+channels_set_policy[ETHTOOL_A_CHANNELS_MAX + 1] = {
+ [ETHTOOL_A_CHANNELS_UNSPEC] = { .type = NLA_REJECT },
+ [ETHTOOL_A_CHANNELS_HEADER] = { .type = NLA_NESTED },
+ [ETHTOOL_A_CHANNELS_RX_MAX] = { .type = NLA_REJECT },
+ [ETHTOOL_A_CHANNELS_TX_MAX] = { .type = NLA_REJECT },
+ [ETHTOOL_A_CHANNELS_OTHER_MAX] = { .type = NLA_REJECT },
+ [ETHTOOL_A_CHANNELS_COMBINED_MAX] = { .type = NLA_REJECT },
+ [ETHTOOL_A_CHANNELS_RX_COUNT] = { .type = NLA_U32 },
+ [ETHTOOL_A_CHANNELS_TX_COUNT] = { .type = NLA_U32 },
+ [ETHTOOL_A_CHANNELS_OTHER_COUNT] = { .type = NLA_U32 },
+ [ETHTOOL_A_CHANNELS_COMBINED_COUNT] = { .type = NLA_U32 },
+};
+
+int ethnl_set_channels(struct sk_buff *skb, struct genl_info *info)
+{
+ struct nlattr *tb[ETHTOOL_A_CHANNELS_MAX + 1];
+ unsigned int from_channel, old_total, i;
+ struct ethtool_channels channels = {};
+ struct ethnl_req_info req_info = {};
+ const struct nlattr *err_attr;
+ const struct ethtool_ops *ops;
+ struct net_device *dev;
+ u32 max_rx_in_use = 0;
+ bool mod = false;
+ int ret;
+
+ ret = nlmsg_parse(info->nlhdr, GENL_HDRLEN, tb,
+ ETHTOOL_A_CHANNELS_MAX, channels_set_policy,
+ info->extack);
+ if (ret < 0)
+ return ret;
+ ret = ethnl_parse_header_dev_get(&req_info,
+ tb[ETHTOOL_A_CHANNELS_HEADER],
+ genl_info_net(info), info->extack,
+ true);
+ if (ret < 0)
+ return ret;
+ dev = req_info.dev;
+ ops = dev->ethtool_ops;
+ ret = -EOPNOTSUPP;
+ if (!ops->get_channels || !ops->set_channels)
+ goto out_dev;
+
+ rtnl_lock();
+ ret = ethnl_ops_begin(dev);
+ if (ret < 0)
+ goto out_rtnl;
+ ops->get_channels(dev, &channels);
+ old_total = channels.combined_count +
+ max(channels.rx_count, channels.tx_count);
+
+ ethnl_update_u32(&channels.rx_count, tb[ETHTOOL_A_CHANNELS_RX_COUNT],
+ &mod);
+ ethnl_update_u32(&channels.tx_count, tb[ETHTOOL_A_CHANNELS_TX_COUNT],
+ &mod);
+ ethnl_update_u32(&channels.other_count,
+ tb[ETHTOOL_A_CHANNELS_OTHER_COUNT], &mod);
+ ethnl_update_u32(&channels.combined_count,
+ tb[ETHTOOL_A_CHANNELS_COMBINED_COUNT], &mod);
+ ret = 0;
+ if (!mod)
+ goto out_ops;
+
+ /* ensure new channel counts are within limits */
+ if (channels.rx_count > channels.max_rx)
+ err_attr = tb[ETHTOOL_A_CHANNELS_RX_COUNT];
+ else if (channels.tx_count > channels.max_tx)
+ err_attr = tb[ETHTOOL_A_CHANNELS_TX_COUNT];
+ else if (channels.other_count > channels.max_other)
+ err_attr = tb[ETHTOOL_A_CHANNELS_OTHER_COUNT];
+ else if (channels.combined_count > channels.max_combined)
+ err_attr = tb[ETHTOOL_A_CHANNELS_COMBINED_COUNT];
+ else
+ err_attr = NULL;
+ if (err_attr) {
+ ret = -EINVAL;
+ NL_SET_ERR_MSG_ATTR(info->extack, err_attr,
+ "requested channel count exceeeds maximum");
+ goto out_ops;
+ }
+
+ /* ensure the new Rx count fits within the configured Rx flow
+ * indirection table settings
+ */
+ if (netif_is_rxfh_configured(dev) &&
+ !ethtool_get_max_rxfh_channel(dev, &max_rx_in_use) &&
+ (channels.combined_count + channels.rx_count) <= max_rx_in_use) {
+ GENL_SET_ERR_MSG(info, "requested channel counts are too low for existing indirection table settings");
+ return -EINVAL;
+ }
+
+ /* Disabling channels, query zero-copy AF_XDP sockets */
+ from_channel = channels.combined_count +
+ min(channels.rx_count, channels.tx_count);
+ for (i = from_channel; i < old_total; i++)
+ if (xdp_get_umem_from_qid(dev, i)) {
+ GENL_SET_ERR_MSG(info, "requested channel counts are too low for existing zerocopy AF_XDP sockets");
+ return -EINVAL;
+ }
+
+ ret = dev->ethtool_ops->set_channels(dev, &channels);
+
+out_ops:
+ ethnl_ops_complete(dev);
+out_rtnl:
+ rtnl_unlock();
+out_dev:
+ dev_put(dev);
+ return ret;
+}
diff --git a/net/ethtool/common.c b/net/ethtool/common.c
index 7b6969af5ae7..0b22741b2f8f 100644
--- a/net/ethtool/common.c
+++ b/net/ethtool/common.c
@@ -258,3 +258,34 @@ int __ethtool_get_link(struct net_device *dev)

return netif_running(dev) && dev->ethtool_ops->get_link(dev);
}
+
+int ethtool_get_max_rxfh_channel(struct net_device *dev, u32 *max)
+{
+ u32 dev_size, current_max = 0;
+ u32 *indir;
+ int ret;
+
+ if (!dev->ethtool_ops->get_rxfh_indir_size ||
+ !dev->ethtool_ops->get_rxfh)
+ return -EOPNOTSUPP;
+ dev_size = dev->ethtool_ops->get_rxfh_indir_size(dev);
+ if (dev_size == 0)
+ return -EOPNOTSUPP;
+
+ indir = kcalloc(dev_size, sizeof(indir[0]), GFP_USER);
+ if (!indir)
+ return -ENOMEM;
+
+ ret = dev->ethtool_ops->get_rxfh(dev, indir, NULL, NULL);
+ if (ret)
+ goto out;
+
+ while (dev_size--)
+ current_max = max(current_max, indir[dev_size]);
+
+ *max = current_max;
+
+out:
+ kfree(indir);
+ return ret;
+}
diff --git a/net/ethtool/common.h b/net/ethtool/common.h
index 7dc1163800a7..03946e16e623 100644
--- a/net/ethtool/common.h
+++ b/net/ethtool/common.h
@@ -29,5 +29,6 @@ int __ethtool_get_link(struct net_device *dev);
bool convert_legacy_settings_to_link_ksettings(
struct ethtool_link_ksettings *link_ksettings,
const struct ethtool_cmd *legacy_settings);
+int ethtool_get_max_rxfh_channel(struct net_device *dev, u32 *max);

#endif /* _ETHTOOL_COMMON_H */
diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index 1d5c1b6b81a4..06224a03139e 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -929,37 +929,6 @@ void netdev_rss_key_fill(void *buffer, size_t len)
}
EXPORT_SYMBOL(netdev_rss_key_fill);

-static int ethtool_get_max_rxfh_channel(struct net_device *dev, u32 *max)
-{
- u32 dev_size, current_max = 0;
- u32 *indir;
- int ret;
-
- if (!dev->ethtool_ops->get_rxfh_indir_size ||
- !dev->ethtool_ops->get_rxfh)
- return -EOPNOTSUPP;
- dev_size = dev->ethtool_ops->get_rxfh_indir_size(dev);
- if (dev_size == 0)
- return -EOPNOTSUPP;
-
- indir = kcalloc(dev_size, sizeof(indir[0]), GFP_USER);
- if (!indir)
- return -ENOMEM;
-
- ret = dev->ethtool_ops->get_rxfh(dev, indir, NULL, NULL);
- if (ret)
- goto out;
-
- while (dev_size--)
- current_max = max(current_max, indir[dev_size]);
-
- *max = current_max;
-
-out:
- kfree(indir);
- return ret;
-}
-
static noinline_for_stack int ethtool_get_rxfh_indir(struct net_device *dev,
void __user *useraddr)
{
diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
index ac35513abeed..f61654b8f210 100644
--- a/net/ethtool/netlink.c
+++ b/net/ethtool/netlink.c
@@ -771,6 +771,11 @@ static const struct genl_ops ethtool_genl_ops[] = {
.dumpit = ethnl_default_dumpit,
.done = ethnl_default_done,
},
+ {
+ .cmd = ETHTOOL_MSG_CHANNELS_SET,
+ .flags = GENL_UNS_ADMIN_PERM,
+ .doit = ethnl_set_channels,
+ },
};

static const struct genl_multicast_group ethtool_nl_mcgrps[] = {
diff --git a/net/ethtool/netlink.h b/net/ethtool/netlink.h
index 53bfe720ff1a..45aad99a6021 100644
--- a/net/ethtool/netlink.h
+++ b/net/ethtool/netlink.h
@@ -349,5 +349,6 @@ int ethnl_set_wol(struct sk_buff *skb, struct genl_info *info);
int ethnl_set_features(struct sk_buff *skb, struct genl_info *info);
int ethnl_set_privflags(struct sk_buff *skb, struct genl_info *info);
int ethnl_set_rings(struct sk_buff *skb, struct genl_info *info);
+int ethnl_set_channels(struct sk_buff *skb, struct genl_info *info);

#endif /* _NET_ETHTOOL_NETLINK_H */
--
2.25.1