linux-kernel - [PATCH v2 3/3] of: Add notifier in of_reconfig_notifier

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Message-Id: <20241110-of-alias-v2-3-16da9844a93e@beagleboard.org>
Date: Sun, 10 Nov 2024 01:21:35 +0530
From: Ayush Singh <ayush@...gleboard.org>
To: Rob Herring <robh@...nel.org>, Saravana Kannan <saravanak@...gle.com>, 
 d-gole@...com, jkridner@...gleboard.org, lorforlinux@...gleboard.org, 
 Geert Uytterhoeven <geert@...ux-m68k.org>, Andrew Davis <afd@...com>, 
 robertcnelson@...gleboard.org
Cc: devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Ayush Singh <ayush@...gleboard.org>
Subject: [PATCH v2 3/3] of: Add notifier in of_reconfig_notifier_register()

Currently the list of aliases is not updated when an overlay that
modifies /aliases is added or removed. This breaks drivers (e.g. serial)
that rely on of_alias_get_id().

Update the list of aliases when a property of the /aliases node is
added, removed, or updated by registering a notifier.

Co-developed-by: Geert Uytterhoeven <geert@...ux-m68k.org>
Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
Signed-off-by: Ayush Singh <ayush@...gleboard.org>
---
 drivers/of/base.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 1cfb3cd4493e17d16868981288115798c6a6a151..5c061fdca885973d4389c0f6afe459a751d850b8 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -235,11 +235,50 @@ static void of_alias_destroy(const char *name, void (*dt_free)(void *))
 	}
 }
 
+static void *alias_alloc(u64 size, u64 align)
+{
+	return kzalloc(size, GFP_KERNEL);
+}
+
+static void alias_free(void *p)
+{
+	/* Leak memory */
+}
+
+static int alias_OF_notifier(struct notifier_block *np, unsigned long action,
+			     void *data)
+{
+	struct of_reconfig_data *reconf_data = data;
+
+	if (reconf_data->dn != of_aliases)
+		return NOTIFY_DONE;
+
+	switch (action) {
+	case OF_RECONFIG_ADD_PROPERTY:
+		of_alias_create(reconf_data->prop, alias_alloc);
+		break;
+	case OF_RECONFIG_REMOVE_PROPERTY:
+		of_alias_destroy(reconf_data->prop->name, alias_free);
+		break;
+	case OF_RECONFIG_UPDATE_PROPERTY:
+		of_alias_destroy(reconf_data->old_prop->name, alias_free);
+		of_alias_create(reconf_data->prop, alias_alloc);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block alias_of_nb = {
+	.notifier_call = alias_OF_notifier,
+};
+
 void __init of_core_init(void)
 {
 	struct device_node *np;
 
 	of_platform_register_reconfig_notifier();
+	of_reconfig_notifier_register(&alias_of_nb);
 
 	/* Create the kset, and register existing nodes */
 	mutex_lock(&of_mutex);

-- 
2.47.0