linux-kernel - [PATCH 5.4 11/71] platform/x86: dell-smbios-wmi: Fix oops on rmmod dell

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Date:   Mon, 24 May 2021 17:25:17 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Mario Limonciello <mario.limonciello@...look.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <mgross@...ux.intel.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 11/71] platform/x86: dell-smbios-wmi: Fix oops on rmmod dell_smbios

From: Hans de Goede <hdegoede@...hat.com>

[ Upstream commit 3a53587423d25c87af4b4126a806a0575104b45e ]

init_dell_smbios_wmi() only registers the dell_smbios_wmi_driver on systems
where the Dell WMI interface is supported. While exit_dell_smbios_wmi()
unregisters it unconditionally, this leads to the following oops:

[  175.722921] ------------[ cut here ]------------
[  175.722925] Unexpected driver unregister!
[  175.722939] WARNING: CPU: 1 PID: 3630 at drivers/base/driver.c:194 driver_unregister+0x38/0x40
...
[  175.723089] Call Trace:
[  175.723094]  cleanup_module+0x5/0xedd [dell_smbios]
...
[  175.723148] ---[ end trace 064c34e1ad49509d ]---

Make the unregister happen on the same condition the register happens
to fix this.

Cc: Mario Limonciello <mario.limonciello@...look.com>
Fixes: 1a258e670434 ("platform/x86: dell-smbios-wmi: Add new WMI dispatcher driver")
Signed-off-by: Hans de Goede <hdegoede@...hat.com>
Reviewed-by: Mario Limonciello <mario.limonciello@...look.com>
Reviewed-by: Mark Gross <mgross@...ux.intel.com>
Link: https://lore.kernel.org/r/20210518125027.21824-1-hdegoede@redhat.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/platform/x86/dell-smbios-wmi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/dell-smbios-wmi.c b/drivers/platform/x86/dell-smbios-wmi.c
index 27a298b7c541..c97bd4a45242 100644
--- a/drivers/platform/x86/dell-smbios-wmi.c
+++ b/drivers/platform/x86/dell-smbios-wmi.c
@@ -271,7 +271,8 @@ int init_dell_smbios_wmi(void)
 
 void exit_dell_smbios_wmi(void)
 {
-	wmi_driver_unregister(&dell_smbios_wmi_driver);
+	if (wmi_supported)
+		wmi_driver_unregister(&dell_smbios_wmi_driver);
 }
 
 MODULE_DEVICE_TABLE(wmi, dell_smbios_wmi_id_table);
-- 
2.30.2