[PATCH net-next v4 8/8] ethtool: add compat for devlink info

[Jakub Kicinski <jakub.kicinski@netronome.com>]

If driver did not fill the fw_version field, try to call into
the new devlink get_info op and collect the versions that way.
We assume ethtool was always reporting running versions.

v4:
 - use IS_REACHABLE() to avoid problems with DEVLINK=m (kbuildbot).
v3 (Jiri):
 - do a dump and then parse it instead of special handling;
 - concatenate all versions (well, all that fit :)).

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
---
 include/net/devlink.h | 10 +++++++
 net/core/devlink.c    | 63 +++++++++++++++++++++++++++++++++++++++++++
 net/core/ethtool.c    |  7 +++++
 3 files changed, 80 insertions(+)

diff --git a/include/net/devlink.h b/include/net/devlink.h
index 6b417f141fd6..1c8523920f66 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -972,4 +972,14 @@ devlink_info_version_running_put(struct devlink_info_req *req,
 }
 #endif
 
+#if IS_REACHABLE(CONFIG_NET_DEVLINK)
+void devlink_compat_running_version(struct net_device *dev,
+				    char *buf, size_t len);
+#else
+static inline void
+devlink_compat_running_version(struct net_device *dev, char *buf, size_t len)
+{
+}
+#endif
+
 #endif /* _NET_DEVLINK_H_ */
diff --git a/net/core/devlink.c b/net/core/devlink.c
index e31b6d617837..eb839d74bcc0 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -5278,6 +5278,69 @@ int devlink_region_snapshot_create(struct devlink_region *region, u64 data_len,
 }
 EXPORT_SYMBOL_GPL(devlink_region_snapshot_create);
 
+static void __devlink_compat_running_version(struct devlink *devlink,
+					     char *buf, size_t len)
+{
+	const struct nlattr *nlattr;
+	struct devlink_info_req req;
+	struct sk_buff *msg;
+	int rem, err;
+
+	if (!devlink->ops->info_get)
+		return;
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg)
+		return;
+
+	req.msg = msg;
+	err = devlink->ops->info_get(devlink, &req, NULL);
+	if (err)
+		goto free_msg;
+
+	nla_for_each_attr(nlattr, (void *)msg->data, msg->len, rem) {
+		const struct nlattr *kv;
+		int rem_kv;
+
+		if (nla_type(nlattr) != DEVLINK_ATTR_INFO_VERSION_RUNNING)
+			continue;
+
+		nla_for_each_nested(kv, nlattr, rem_kv) {
+			if (nla_type(kv) != DEVLINK_ATTR_INFO_VERSION_VALUE)
+				continue;
+
+			strlcat(buf, nla_data(kv), len);
+			strlcat(buf, " ", len);
+		}
+	}
+free_msg:
+	nlmsg_free(msg);
+}
+
+void devlink_compat_running_version(struct net_device *dev,
+				    char *buf, size_t len)
+{
+	struct devlink_port *devlink_port;
+	struct devlink *devlink;
+
+	mutex_lock(&devlink_mutex);
+	list_for_each_entry(devlink, &devlink_list, list) {
+		mutex_lock(&devlink->lock);
+		list_for_each_entry(devlink_port, &devlink->port_list, list) {
+			if (devlink_port->type == DEVLINK_PORT_TYPE_ETH ||
+			    devlink_port->type_dev == dev) {
+				__devlink_compat_running_version(devlink,
+								 buf, len);
+				mutex_unlock(&devlink->lock);
+				goto out;
+			}
+		}
+		mutex_unlock(&devlink->lock);
+	}
+out:
+	mutex_unlock(&devlink_mutex);
+}
+
 static int __init devlink_module_init(void)
 {
 	return genl_register_family(&devlink_nl_family);
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 158264f7cfaf..197a4dfb712d 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -27,6 +27,7 @@
 #include <linux/rtnetlink.h>
 #include <linux/sched/signal.h>
 #include <linux/net.h>
+#include <net/devlink.h>
 #include <net/xdp_sock.h>
 
 /*
@@ -803,6 +804,12 @@ static noinline_for_stack int ethtool_get_drvinfo(struct net_device *dev,
 	if (ops->get_eeprom_len)
 		info.eedump_len = ops->get_eeprom_len(dev);
 
+	rtnl_unlock();
+	if (!info.fw_version[0])
+		devlink_compat_running_version(dev, info.fw_version,
+					       sizeof(info.fw_version));
+	rtnl_lock();
+
 	if (copy_to_user(useraddr, &info, sizeof(info)))
 		return -EFAULT;
 	return 0;
-- 
2.19.2