Merge branch 'devlink-make-ethtool-compat-reliable'

Jakub Kicinski says:

====================
devlink: make ethtool compat reliable

This is a follow up to the series which added device flash
updates via devlink. I went with the approach of adding a
new NDO in the end. It seems to end up looking cleaner.

First patch removes the option to build devlink as a module.
Users can still decide to not build it, but the module option
ends up not being worth the maintenance cost.

Next two patches add a NDO which can be used to ask the driver
to return a devlink instance associated with a given netdev,
instead of iterating over devlink ports. Drivers which implement
this NDO must take into account the potential impact on the
visibility of the devlink instance.

With the new NDO in place we can remove NFP ethtool flash update
code.

Fifth patch makes sure we hold a reference to dev while
callbacks are active.

Last but not least the NULL-check of devlink->ops is moved
to instance allocation time.

Last but not least missing checks for devlink->ops are added.
There is currently no driver registering devlink without ops,
so can just fix this in -next.

v2 (Michal): add netdev_to_devlink() in patch 3.
v3 (Florian):
 - add missing checks for devlink->ops;
 - move locking/holding into devlink_compat_ functions.
v4 (Jiri):
 - hold devlink_mutex around callbacks (patch 2);
 - require non-NULL ops (patch 6).
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 20 insertions, 6 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index ffbddd03242b..58e83bd7a861 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -941,6 +941,8 @@ struct dev_ifalias {
 	char ifalias[];
 };
 
+struct devlink;
+
 /*
  * This structure defines the management hooks for network devices.
  * The following hooks can be defined; unless noted otherwise, they are
@@ -1249,6 +1251,10 @@ struct dev_ifalias {
  *	that got dropped are freed/returned via xdp_return_frame().
  *	Returns negative number, means general error invoking ndo, meaning
  *	no frames were xmit'ed and core-caller will free all frames.
+ * struct devlink *(*ndo_get_devlink)(struct net_device *dev);
+ *	Get devlink instance associated with a given netdev.
+ *	Called with a reference on the netdevice and devlink locks only,
+ *	rtnl_lock is not held.
  */
 struct net_device_ops {
 	int			(*ndo_init)(struct net_device *dev);
@@ -1447,6 +1453,7 @@ struct net_device_ops {
 						u32 flags);
 	int			(*ndo_xsk_async_xmit)(struct net_device *dev,
 						      u32 queue_id);
+	struct devlink *	(*ndo_get_devlink)(struct net_device *dev);
 };
 
 /**
diff --git a/include/net/devlink.h b/include/net/devlink.h
index a2da49dd9147..7f5a0bdca228 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -538,6 +538,15 @@ static inline struct devlink *priv_to_devlink(void *priv)
 	return container_of(priv, struct devlink, priv);
 }
 
+static inline struct devlink *netdev_to_devlink(struct net_device *dev)
+{
+#if IS_ENABLED(CONFIG_NET_DEVLINK)
+	if (dev->netdev_ops->ndo_get_devlink)
+		return dev->netdev_ops->ndo_get_devlink(dev);
+#endif
+	return NULL;
+}
+
 struct ib_device;
 
 #if IS_ENABLED(CONFIG_NET_DEVLINK)
@@ -707,6 +716,10 @@ devlink_health_reporter_priv(struct devlink_health_reporter *reporter);
 int devlink_health_report(struct devlink_health_reporter *reporter,
 			  const char *msg, void *priv_ctx);
 
+void devlink_compat_running_version(struct net_device *dev,
+				    char *buf, size_t len);
+int devlink_compat_flash_update(struct net_device *dev, const char *file_name);
+
 #else
 
 static inline struct devlink *devlink_alloc(const struct devlink_ops *ops,
@@ -1190,13 +1203,7 @@ devlink_health_report(struct devlink_health_reporter *reporter,
 {
 	return 0;
 }
-#endif
 
-#if IS_REACHABLE(CONFIG_NET_DEVLINK)
-void devlink_compat_running_version(struct net_device *dev,
-				    char *buf, size_t len);
-int devlink_compat_flash_update(struct net_device *dev, const char *file_name);
-#else
 static inline void
 devlink_compat_running_version(struct net_device *dev, char *buf, size_t len)
 {