[PATCH] net: dev: Add API to check net_dev readiness

Ilia Lin
2020-07-26T19:38:02Z

From: Ilia Lin <ilia.lin@kernel.org>

Add an API that returns true, if the net_dev_init was already called,
and the driver was initialized.

Some early drivers, that are initialized during the subsys_initcall
may try accessing the net_dev or NAPI APIs before the net_dev_init,
and will encounter a kernel bug. This API provides a way to handle
this and manage by deferring or by other way.

Signed-off-by: Ilia Lin <ilia.lin@kernel.org>
---
include/linux/netdevice.h | 2 ++
net/core/dev.c | 17 +++++++++++++++++
2 files changed, 19 insertions(+)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 98d290c..d17d364 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2600,6 +2600,8 @@ enum netdev_cmd {
};
const char *netdev_cmd_to_name(enum netdev_cmd cmd);

+bool is_net_dev_initialized(void);
+
int register_netdevice_notifier(struct notifier_block *nb);
int unregister_netdevice_notifier(struct notifier_block *nb);
int register_netdevice_notifier_net(struct net *net, struct notifier_block *nb);
diff --git a/net/core/dev.c b/net/core/dev.c
index 316349f..1b50488 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1793,6 +1793,23 @@ static void call_netdevice_unregister_net_notifiers(struct notifier_block *nb,
static int dev_boot_phase = 1;

/**
+ * is_net_dev_initialized - check, whether the net_dev was
+ * initialized
+ *
+ * Returns true, if the net_dev_init was already called, and
+ * the driver is initialized.
+ *
+ * This is useful for early drivers trying to call net_dev and
+ * NAPI APIs
+ */
+
+bool is_net_dev_initialized(void)
+{
+ return !(bool)dev_boot_phase;
+}
+EXPORT_SYMBOL(is_net_dev_initialized);
+
+/**
* register_netdevice_notifier - register a network notifier block
* @nb: notifier
*