linux-kernel - Re: [lkp-robot] [platform/x86] bff589be59: kmsg.dell_wmi:Cannot_read_Dell_descriptor

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Date:   Thu, 20 Jul 2017 18:23:30 +0200
From:   Pali Rohár <pali.rohar@...il.com>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     Darren Hart <dvhart@...radead.org>,
        Andy Lutomirski <luto@...capital.net>,
        Mario Limonciello <mario_limonciello@...l.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>, lkp@...org,
        kernel test robot <xiaolong.ye@...el.com>
Subject: Re: [lkp-robot] [platform/x86]  bff589be59:
 kmsg.dell_wmi:Cannot_read_Dell_descriptor_buffer

On Thursday 20 July 2017 09:02:20 kernel test robot wrote:
> commit: bff589be59c50924a9715951160578e570cba5c6 ("platform/x86: dell-wmi: Convert to the WMI bus infrastructure")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> 
> caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):
> 
> [    7.104086] dell_wmi: Cannot read Dell descriptor buffer - 1

Hi Andy! Problem is in following code:

static int __init dell_wmi_init(void)
{
	int err;

	err = dell_wmi_check_descriptor_buffer();
	if (err)
		return err;

	dmi_check_system(dell_wmi_smbios_list);

	if (wmi_requires_smbios_request) {
		err = dell_wmi_events_set_enabled(true);
		if (err) {
			pr_err("Failed to enable WMI events\n");
			return err;
		}
	}

	return wmi_driver_register(&dell_wmi_driver);
}
module_init(dell_wmi_init);

static void __exit dell_wmi_exit(void)
{
	if (wmi_requires_smbios_request)
		dell_wmi_events_set_enabled(false);

	wmi_driver_unregister(&dell_wmi_driver);
}
module_exit(dell_wmi_exit);

dell_wmi_init and dell_wmi_exit should just call wmi_driver_register and
wmi_driver_unregister.

All those other calls (like different checks or enabling wmi events)
should be done in dell_wmi_probe from dell_wmi_driver structure. Same
for dell_wmi_remove.

Basically with this bus interface you should be able to load dell-wmi.ko
also on non-dell machines. Just bus code would not create and register
wmi device and so no probe would be called.

-- 
Pali Rohár
pali.rohar@...il.com