Merge branch 'autoload-dsa-tagging-driver-when-dynamically-changing-protocol'

Vladimir Oltean says:

====================
Autoload DSA tagging driver when dynamically changing protocol

This patch set solves the issue reported by Michael and Heiko here:
https://lore.kernel.org/lkml/20221027113248.420216-1-michael@walle.cc/
making full use of Michael's suggestion of having two modaliases: one
gets used for loading the tagging protocol when it's the default one
reported by the switch driver, the other gets loaded at user's request,
by name.

  # modinfo tag_ocelot
  filename:       /lib/modules/6.1.0-rc4+/kernel/net/dsa/tag_ocelot.ko
  license:        GPL v2
  alias:          dsa_tag:seville
  alias:          dsa_tag:id-21
  alias:          dsa_tag:ocelot
  alias:          dsa_tag:id-15
  depends:        dsa_core
  intree:         Y
  name:           tag_ocelot
  vermagic:       6.1.0-rc4+ SMP preempt mod_unload modversions aarch64

Tested on NXP LS1028A-RDB with the following device tree addition:

&mscc_felix_port4 {
	dsa-tag-protocol = "ocelot-8021q";
};

&mscc_felix_port5 {
	dsa-tag-protocol = "ocelot-8021q";
};

CONFIG_NET_DSA and everything that depends on it is built as module.
Everything auto-loads, and "cat /sys/class/net/eno2/dsa/tagging" shows
"ocelot-8021q". Traffic works as well. Furthermore, "echo ocelot-8021q"
into the aforementioned sysfs file now auto-loads the driver for it.
====================

Link: https://lore.kernel.org/r/20221115011847.2843127-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 6caf2ec648fd..4afd3edbd64d 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -79,16 +79,18 @@ const char *dsa_tag_protocol_to_str(const struct dsa_device_ops *ops)
 /* Function takes a reference on the module owning the tagger,
  * so dsa_tag_driver_put must be called afterwards.
  */
-const struct dsa_device_ops *dsa_find_tagger_by_name(const char *buf)
+const struct dsa_device_ops *dsa_tag_driver_get_by_name(const char *name)
 {
 	const struct dsa_device_ops *ops = ERR_PTR(-ENOPROTOOPT);
 	struct dsa_tag_driver *dsa_tag_driver;
 
+	request_module("%s%s", DSA_TAG_DRIVER_ALIAS, name);
+
 	mutex_lock(&dsa_tag_drivers_lock);
 	list_for_each_entry(dsa_tag_driver, &dsa_tag_drivers_list, list) {
 		const struct dsa_device_ops *tmp = dsa_tag_driver->ops;
 
-		if (!sysfs_streq(buf, tmp->name))
+		if (strcmp(name, tmp->name))
 			continue;
 
 		if (!try_module_get(dsa_tag_driver->owner))
@@ -102,13 +104,13 @@ const struct dsa_device_ops *dsa_find_tagger_by_name(const char *buf)
 	return ops;
 }
 
-const struct dsa_device_ops *dsa_tag_driver_get(int tag_protocol)
+const struct dsa_device_ops *dsa_tag_driver_get_by_id(int tag_protocol)
 {
 	struct dsa_tag_driver *dsa_tag_driver;
 	const struct dsa_device_ops *ops;
 	bool found = false;
 
-	request_module("%s%d", DSA_TAG_DRIVER_ALIAS, tag_protocol);
+	request_module("%sid-%d", DSA_TAG_DRIVER_ALIAS, tag_protocol);
 
 	mutex_lock(&dsa_tag_drivers_lock);
 	list_for_each_entry(dsa_tag_driver, &dsa_tag_drivers_list, list) {