On 15/02/17 06:05, Cheah Kok Cheong wrote:
On Mon, Feb 13, 2017 at 11:14:14AM +0000, Ian Abbott wrote:
On 11/02/17 10:37, Cheah Kok Cheong wrote:
[snip]
+static void __exit comedi_test_exit(void)
+{
+       comedi_auto_unconfig(ctdev);
+
+       device_destroy(ctcls, MKDEV(0, 0));
+
+       class_destroy(ctcls);


If the driver init returned successfully, but failed to set-up the
auto-configured device, the device and class will not exist at this point,
so those three calls need to go in an 'if' statement.  Perhaps you could use
'if (ctcls) {', and set 'ctcls = NULL;' after calling
'class_destroy(ctcls);' in the init function.

Apart from that, it looks fine.


Thanks for pointing out those two pointers have to be "NULL" if
auto-configuration fails.

Please review below snippet.
Sorry for the inconvenience caused.

[ Snip ]

static int __init comedi_test_init(void)
{
        int ret;

        ret = comedi_driver_register(&waveform_driver);
        if (ret) {
                pr_err("comedi_test: unable to register driver\n");
                return ret;
        }

        if (!config_mode) {
                ctcls = class_create(THIS_MODULE, CLASS_NAME);
                if (IS_ERR(ctcls)) {
                        pr_warn("comedi_test: unable to create class\n");
                        goto clean3;
                }

                ctdev = device_create(ctcls, NULL, MKDEV(0, 0), NULL, DEV_NAME);
                if (IS_ERR(ctdev)) {
                        pr_warn("comedi_test: unable to create device\n");
                        goto clean2;
                }

                ret = comedi_auto_config(ctdev, &waveform_driver, 0);
                if (ret) {
                        pr_warn("comedi_test: unable to auto-configure 
device\n");
                        goto clean;
                }
        }

        return 0;

clean:
        device_destroy(ctcls, MKDEV(0, 0));
clean2:
        class_destroy(ctcls);
        ctdev = NULL;
clean3:
        ctcls = NULL;

        return 0;
}
module_init(comedi_test_init);

static void __exit comedi_test_exit(void)
{
        if (ctdev)
                comedi_auto_unconfig(ctdev);

        if (ctcls) {
                device_destroy(ctcls, MKDEV(0, 0));
                class_destroy(ctcls);
        }

        comedi_driver_unregister(&waveform_driver);
}
module_exit(comedi_test_exit);

[ Snip ]

Thks.
Brgds,
CheahKC


Yes, that looks fine.

--
-=( Ian Abbott @ MEV Ltd.    E-mail: <abbo...@mev.co.uk> )=-
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