Re: [PATCH 2/2] platform/x86: Add Intel Software Defined Silicon driver

On Fri, Sep 24, 2021 at 02:31:57PM -0700, David E. Box wrote:

Quick review:

+static int sdsi_probe(struct platform_device *pdev)
+{
+	void __iomem *disc_addr;
+	struct sdsi_priv *priv;
+	int ret;
+
+	disc_addr = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(disc_addr))
+		return PTR_ERR(disc_addr);
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	kref_init(&priv->kref);
+
+	platform_set_drvdata(pdev, priv);
+	priv->pdev = pdev;
+	mutex_init(&priv->mb_lock);
+	mutex_init(&priv->akc_lock);
+
+	memcpy_fromio(&priv->disc_table, disc_addr, DISC_TABLE_SIZE);
+
+	ret = sdsi_map_sdsi_registers(pdev);
+	if (ret)
+		goto put_kref;
+
+	ret = sdsi_create_misc_device(pdev);
+	if (ret)
+		goto put_kref;
+
+	ret = sdsi_add_bin_attrs(pdev);

You just raced with userspace and lost.  Please attach your attributes
to the misc device before registering it.

Also, you need a Documentation/ABI/ entry for your new sysfs file(s).

+	if (ret)
+		goto deregister_misc;
+
+	priv->dev_present = true;
+
+	return 0;
+
+deregister_misc:
+	misc_deregister(&priv->miscdev);
+put_kref:
+	kref_put(&priv->kref, sdsi_priv_release);
+
+	return ret;
+}
+
+static int sdsi_remove(struct platform_device *pdev)
+{
+	struct sdsi_priv *priv = platform_get_drvdata(pdev);
+
+	priv->dev_present = false;
+	sysfs_remove_bin_file(&priv->pdev->dev.kobj, &priv->registers_bin_attr);
+	misc_deregister(&priv->miscdev);
+	kref_put(&priv->kref, sdsi_priv_release);

Why do you need a kref for a structure that already can be controlled by
a different lifetime rule?

+
+	return 0;
+}
+
+static struct platform_driver sdsi_driver = {
+	.driver = {
+		.name		= SDSI_DEV_NAME,
+		.dev_groups	= sdsi_groups,
+	},
+	.probe  = sdsi_probe,
+	.remove = sdsi_remove,
+};
+module_platform_driver(sdsi_driver);

What causes the platform to know to register, and enable, this platform
driver?  Shouldn't there be some hardware involved that is discoverable
to enable it to load dynamically?

thanks,

greg k-h