[PATCH v3 10/12] crypto: atmel-sha204a - integrate into core management tracking

[Lothar Rubusch <l.rubusch@gmail.com>]

Register the SHA204A I2C device instance into the shared atmel_i2c client
management tracking list during the probe phase. This allows the driver to
participate in the central hardware selection infrastructure.

Rework the error-unwind paths inside atmel_sha204a_probe() to prevent stale
entries from remaining in the global tracking structures if a partial
initialization failure occurs. If sysfs group creation fails, explicitly
trigger devm_hwrng_unregister() to preserve the strict lifecycle ordering
introduced in previous stability fixes.

Convert the removal path to use the core teardown helpers. Ensure the
device readiness state is deactivated using atmel_i2c_deactivate_client()
and the tracking node is removed via atmel_i2c_unregister_client() before
local memory resources are freed. This guarantees that any in-flight work
queue items are unconditionally flushed, eliminating a potential
Use-After-Free (UAF) window during device removal.

No functional change intended beyond improved lifecycle handling.

Signed-off-by: Lothar Rubusch <l.rubusch@gmail.com>
---
 drivers/crypto/atmel-sha204a.c | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/drivers/crypto/atmel-sha204a.c b/drivers/crypto/atmel-sha204a.c
index 3853d2b95449..db61ac0177f6 100644
--- a/drivers/crypto/atmel-sha204a.c
+++ b/drivers/crypto/atmel-sha204a.c
@@ -172,9 +172,15 @@ static int atmel_sha204a_probe(struct i2c_client *client)
 		return ret;
 
 	i2c_priv = i2c_get_clientdata(client);
+	i2c_priv->ready = false;
 
 	i2c_priv->caps = 0;
 
+	spin_lock(&atmel_i2c_mgmt.i2c_list_lock);
+	list_add_tail(&i2c_priv->i2c_client_list_node,
+		      &atmel_i2c_mgmt.i2c_client_list);
+	spin_unlock(&atmel_i2c_mgmt.i2c_list_lock);
+
 	memset(&i2c_priv->hwrng, 0, sizeof(i2c_priv->hwrng));
 
 	i2c_priv->hwrng.name = dev_name(&client->dev);
@@ -185,15 +191,28 @@ static int atmel_sha204a_probe(struct i2c_client *client)
 		i2c_priv->hwrng.quality = *quality;
 
 	ret = devm_hwrng_register(&client->dev, &i2c_priv->hwrng);
-	if (ret)
+	if (ret) {
 		dev_warn(&client->dev, "failed to register RNG (%d)\n", ret);
+		goto err_list_del;
+	}
 
 	ret = sysfs_create_group(&client->dev.kobj, &atmel_sha204a_groups);
 	if (ret) {
 		dev_err(&client->dev, "failed to register sysfs entry\n");
-		return ret;
+		goto err_hwrng_unregister;
 	}
 
+	spin_lock(&atmel_i2c_mgmt.i2c_list_lock);
+	i2c_priv->ready = true;
+	spin_unlock(&atmel_i2c_mgmt.i2c_list_lock);
+
+	return 0;
+
+err_hwrng_unregister:
+	devm_hwrng_unregister(&client->dev, &i2c_priv->hwrng);
+err_list_del:
+	atmel_i2c_unregister_client(i2c_priv);
+
 	return ret;
 }
 
@@ -201,9 +220,10 @@ static void atmel_sha204a_remove(struct i2c_client *client)
 {
 	struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
 
-	devm_hwrng_unregister(&client->dev, &i2c_priv->hwrng);
-	atmel_i2c_flush_queue();
+	atmel_i2c_deactivate_client(i2c_priv);
 
+	devm_hwrng_unregister(&client->dev, &i2c_priv->hwrng);
+	atmel_i2c_unregister_client(i2c_priv);
 	sysfs_remove_group(&client->dev.kobj, &atmel_sha204a_groups);
 
 	kfree((void *)i2c_priv->hwrng.priv);
@@ -239,7 +259,6 @@ static int __init atmel_sha204a_init(void)
 
 static void __exit atmel_sha204a_exit(void)
 {
-	atmel_i2c_flush_queue();
 	i2c_del_driver(&atmel_sha204a_driver);
 }
 
-- 
2.39.5