[PATCH v2 0/7] platform/x86: dell-wmi-sysman: Various error-handling and robustness fixes

[PATCH v2 0/7] platform/x86: dell-wmi-sysman: Various error-handling and robustness fixes

[Hans de Goede]

Hi All,

There have been several bug-reports about crashes related to the
dell-wmi-sysman module:

https://bugzilla.redhat.com/show_bug.cgi?id=1936171
https://bugzilla.kernel.org/show_bug.cgi?id=211895
https://bugs.archlinux.org/task/69702

Here is v2 of my series with a bunch of fixes for NULL pointer derefs,
double-frees, etc. which fixes this.

New in v2:
-New patch: "platform/x86: dell-wmi-sysman: Fix crash caused by calling 
kset_unregister twice" which addresses the direct-cause of
the crash.  Note that the crash was already fixed in v1 because
that removed the code-path where kset_unregister ended up being
called twice.

-Dropped: "platform/x86: dell-wmi-sysman: Make init_bios_attributes() 
ACPI object parsing more robust". This needs more testing / discussion
and is not necessary to fix the boot-failure which people are seeing.

Regards,

Hans


Hans de Goede (7):
  platform/x86: dell-wmi-sysman: Fix crash caused by calling
    kset_unregister twice
  platform/x86: dell-wmi-sysman: Fix possible NULL pointer deref on exit
  platform/x86: dell-wmi-sysman: Make it safe to call
    exit_foo_attributes() multiple times
  platform/x86: dell-wmi-sysman: Fix release_attributes_data() getting
    called twice on init_bios_attributes() failure
  platform/x86: dell-wmi-sysman: Cleanup sysman_init() error-exit
    handling
  platform/x86: dell-wmi-sysman: Make sysman_init() return -ENODEV of
    the interfaces are not found
  platform/x86: dell-wmi-sysman: Cleanup
    create_attributes_level_sysfs_files()

 .../dell/dell-wmi-sysman/enum-attributes.c    |  3 +
 .../x86/dell/dell-wmi-sysman/int-attributes.c |  3 +
 .../dell/dell-wmi-sysman/passobj-attributes.c |  3 +
 .../dell/dell-wmi-sysman/string-attributes.c  |  3 +
 .../x86/dell/dell-wmi-sysman/sysman.c         | 84 +++++++------------
 5 files changed, 44 insertions(+), 52 deletions(-)

-- 
2.30.2

[PATCH v2 1/7] platform/x86: dell-wmi-sysman: Fix crash caused by calling kset_unregister twice

[Hans de Goede]

On some system the WMI GUIDs used by dell-wmi-sysman are present but there
are no enum type attributes, this causes init_bios_attributes() to return
-ENODEV, after which sysman_init() does a "goto fail_create_group" and then
calls release_attributes_data().

release_attributes_data() calls kset_unregister(wmi_priv.main_dir_kset);
but before this commit it was missing a "wmi_priv.main_dir_kset = NULL;"
statement; and after calling release_attributes_data() the sysman_init()
error handling does this:

        if (wmi_priv.main_dir_kset) {
                kset_unregister(wmi_priv.main_dir_kset);
                wmi_priv.main_dir_kset = NULL;
        }

Which causes a second kset_unregister(wmi_priv.main_dir_kset), leading to
a double-free, which causes a crash.

Add the missing "wmi_priv.main_dir_kset = NULL;" statement to
release_attributes_data() to fix this double-free crash.

Fixes: e8a60aa7404b ("platform/x86: Introduce support for Systems Management Driver over WMI for Dell Systems")
Cc: Divya Bharathi <Divya_Bharathi@dell.com>
Cc: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/platform/x86/dell/dell-wmi-sysman/sysman.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c b/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
index cb81010ba1a2..c1997db74cca 100644
--- a/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
+++ b/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
@@ -388,6 +388,7 @@ static void release_attributes_data(void)
 	if (wmi_priv.main_dir_kset) {
 		destroy_attribute_objs(wmi_priv.main_dir_kset);
 		kset_unregister(wmi_priv.main_dir_kset);
+		wmi_priv.main_dir_kset = NULL;
 	}
 	mutex_unlock(&wmi_priv.mutex);
 
-- 
2.30.2

[PATCH v2 2/7] platform/x86: dell-wmi-sysman: Fix possible NULL pointer deref on exit

[Hans de Goede]

It is possible for release_attributes_data() to get called when the
main_dir_kset has not been created yet, move the removal of the bios-reset
sysfs attr to under a if (main_dir_kset) check to avoid a NULL pointer
deref.

Fixes: e8a60aa7404b ("platform/x86: Introduce support for Systems Management Driver over WMI for Dell Systems")
Cc: Divya Bharathi <Divya_Bharathi@dell.com>
Cc: Mario Limonciello <mario.limonciello@dell.com>
Reported-by: Alexander Naumann <alexandernaumann@gmx.de>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/platform/x86/dell/dell-wmi-sysman/sysman.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c b/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
index c1997db74cca..8b251b2c37a2 100644
--- a/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
+++ b/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
@@ -225,12 +225,6 @@ static int create_attributes_level_sysfs_files(void)
 	return ret;
 }
 
-static void release_reset_bios_data(void)
-{
-	sysfs_remove_file(&wmi_priv.main_dir_kset->kobj, &reset_bios.attr);
-	sysfs_remove_file(&wmi_priv.main_dir_kset->kobj, &pending_reboot.attr);
-}
-
 static ssize_t wmi_sysman_attr_show(struct kobject *kobj, struct attribute *attr,
 				    char *buf)
 {
@@ -373,8 +367,6 @@ static void destroy_attribute_objs(struct kset *kset)
  */
 static void release_attributes_data(void)
 {
-	release_reset_bios_data();
-
 	mutex_lock(&wmi_priv.mutex);
 	exit_enum_attributes();
 	exit_int_attributes();
@@ -386,12 +378,13 @@ static void release_attributes_data(void)
 		wmi_priv.authentication_dir_kset = NULL;
 	}
 	if (wmi_priv.main_dir_kset) {
+		sysfs_remove_file(&wmi_priv.main_dir_kset->kobj, &reset_bios.attr);
+		sysfs_remove_file(&wmi_priv.main_dir_kset->kobj, &pending_reboot.attr);
 		destroy_attribute_objs(wmi_priv.main_dir_kset);
 		kset_unregister(wmi_priv.main_dir_kset);
 		wmi_priv.main_dir_kset = NULL;
 	}
 	mutex_unlock(&wmi_priv.mutex);
-
 }
 
 /**
-- 
2.30.2

[PATCH v2 3/7] platform/x86: dell-wmi-sysman: Make it safe to call exit_foo_attributes() multiple times

[Hans de Goede]

During some of the error-exit paths it is possible that
release_attributes_data() will get called multiple times,
which results in exit_foo_attributes() getting called multiple
times.

Make it safe to call exit_foo_attributes() multiple times,
avoiding double-free()s in this case.

Note that release_attributes_data() really should only be called
once during error-exit paths. This will be fixed in a separate patch
and it is good to have the exit_foo_attributes() functions modified
this way regardless.

Fixes: e8a60aa7404b ("platform/x86: Introduce support for Systems Management Driver over WMI for Dell Systems")
Cc: Divya Bharathi <Divya_Bharathi@dell.com>
Cc: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/platform/x86/dell/dell-wmi-sysman/enum-attributes.c    | 3 +++
 drivers/platform/x86/dell/dell-wmi-sysman/int-attributes.c     | 3 +++
 drivers/platform/x86/dell/dell-wmi-sysman/passobj-attributes.c | 3 +++
 drivers/platform/x86/dell/dell-wmi-sysman/string-attributes.c  | 3 +++
 4 files changed, 12 insertions(+)

diff --git a/drivers/platform/x86/dell/dell-wmi-sysman/enum-attributes.c b/drivers/platform/x86/dell/dell-wmi-sysman/enum-attributes.c
index 80f4b7785c6c..091e48c217ed 100644
--- a/drivers/platform/x86/dell/dell-wmi-sysman/enum-attributes.c
+++ b/drivers/platform/x86/dell/dell-wmi-sysman/enum-attributes.c
@@ -185,5 +185,8 @@ void exit_enum_attributes(void)
 			sysfs_remove_group(wmi_priv.enumeration_data[instance_id].attr_name_kobj,
 								&enumeration_attr_group);
 	}
+	wmi_priv.enumeration_instances_count = 0;
+
 	kfree(wmi_priv.enumeration_data);
+	wmi_priv.enumeration_data = NULL;
 }
diff --git a/drivers/platform/x86/dell/dell-wmi-sysman/int-attributes.c b/drivers/platform/x86/dell/dell-wmi-sysman/int-attributes.c
index 75aedbb733be..8a49ba6e44f9 100644
--- a/drivers/platform/x86/dell/dell-wmi-sysman/int-attributes.c
+++ b/drivers/platform/x86/dell/dell-wmi-sysman/int-attributes.c
@@ -175,5 +175,8 @@ void exit_int_attributes(void)
 			sysfs_remove_group(wmi_priv.integer_data[instance_id].attr_name_kobj,
 								&integer_attr_group);
 	}
+	wmi_priv.integer_instances_count = 0;
+
 	kfree(wmi_priv.integer_data);
+	wmi_priv.integer_data = NULL;
 }
diff --git a/drivers/platform/x86/dell/dell-wmi-sysman/passobj-attributes.c b/drivers/platform/x86/dell/dell-wmi-sysman/passobj-attributes.c
index 3abcd95477c0..834b3e82ad9f 100644
--- a/drivers/platform/x86/dell/dell-wmi-sysman/passobj-attributes.c
+++ b/drivers/platform/x86/dell/dell-wmi-sysman/passobj-attributes.c
@@ -183,5 +183,8 @@ void exit_po_attributes(void)
 			sysfs_remove_group(wmi_priv.po_data[instance_id].attr_name_kobj,
 								&po_attr_group);
 	}
+	wmi_priv.po_instances_count = 0;
+
 	kfree(wmi_priv.po_data);
+	wmi_priv.po_data = NULL;
 }
diff --git a/drivers/platform/x86/dell/dell-wmi-sysman/string-attributes.c b/drivers/platform/x86/dell/dell-wmi-sysman/string-attributes.c
index ac75dce88a4c..552537852459 100644
--- a/drivers/platform/x86/dell/dell-wmi-sysman/string-attributes.c
+++ b/drivers/platform/x86/dell/dell-wmi-sysman/string-attributes.c
@@ -155,5 +155,8 @@ void exit_str_attributes(void)
 			sysfs_remove_group(wmi_priv.str_data[instance_id].attr_name_kobj,
 								&str_attr_group);
 	}
+	wmi_priv.str_instances_count = 0;
+
 	kfree(wmi_priv.str_data);
+	wmi_priv.str_data = NULL;
 }
-- 
2.30.2

[PATCH v2 4/7] platform/x86: dell-wmi-sysman: Fix release_attributes_data() getting called twice on init_bios_attributes() failure

[Hans de Goede]

All calls of init_bios_attributes() will result in a
goto fail_create_group if they fail, which calls
release_attributes_data().

So there is no need to call release_attributes_data() from
init_bios_attributes() on failure itself.

Fixes: e8a60aa7404b ("platform/x86: Introduce support for Systems Management Driver over WMI for Dell Systems")
Cc: Divya Bharathi <Divya_Bharathi@dell.com>
Cc: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/platform/x86/dell/dell-wmi-sysman/sysman.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c b/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
index 8b251b2c37a2..58dc4571f987 100644
--- a/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
+++ b/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
@@ -491,7 +491,6 @@ static int init_bios_attributes(int attr_type, const char *guid)
 
 err_attr_init:
 	mutex_unlock(&wmi_priv.mutex);
-	release_attributes_data();
 	kfree(obj);
 	return retval;
 }
-- 
2.30.2

[PATCH v2 5/7] platform/x86: dell-wmi-sysman: Cleanup sysman_init() error-exit handling

[Hans de Goede]

Cleanup sysman_init() error-exit handling:

1. There is no need for the fail_reset_bios and fail_authentication_kset
   eror-exit cases, these can be handled by release_attributes_data()

2. Rename all the labels from fail_what_failed, to err_what_to_cleanup
   this is the usual way to name these and avoids the need to rename
   them when extra steps are added.

Fixes: e8a60aa7404b ("platform/x86: Introduce support for Systems Management Driver over WMI for Dell Systems")
Cc: Divya Bharathi <Divya_Bharathi@dell.com>
Cc: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 .../x86/dell/dell-wmi-sysman/sysman.c         | 45 +++++++------------
 1 file changed, 16 insertions(+), 29 deletions(-)

diff --git a/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c b/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
index 58dc4571f987..99dc2f3bdf49 100644
--- a/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
+++ b/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
@@ -508,100 +508,87 @@ static int __init sysman_init(void)
 	ret = init_bios_attr_set_interface();
 	if (ret || !wmi_priv.bios_attr_wdev) {
 		pr_debug("failed to initialize set interface\n");
-		goto fail_set_interface;
+		return ret;
 	}
 
 	ret = init_bios_attr_pass_interface();
 	if (ret || !wmi_priv.password_attr_wdev) {
 		pr_debug("failed to initialize pass interface\n");
-		goto fail_pass_interface;
+		goto err_exit_bios_attr_set_interface;
 	}
 
 	ret = class_register(&firmware_attributes_class);
 	if (ret)
-		goto fail_class;
+		goto err_exit_bios_attr_pass_interface;
 
 	wmi_priv.class_dev = device_create(&firmware_attributes_class, NULL, MKDEV(0, 0),
 				  NULL, "%s", DRIVER_NAME);
 	if (IS_ERR(wmi_priv.class_dev)) {
 		ret = PTR_ERR(wmi_priv.class_dev);
-		goto fail_classdev;
+		goto err_unregister_class;
 	}
 
 	wmi_priv.main_dir_kset = kset_create_and_add("attributes", NULL,
 						     &wmi_priv.class_dev->kobj);
 	if (!wmi_priv.main_dir_kset) {
 		ret = -ENOMEM;
-		goto fail_main_kset;
+		goto err_destroy_classdev;
 	}
 
 	wmi_priv.authentication_dir_kset = kset_create_and_add("authentication", NULL,
 								&wmi_priv.class_dev->kobj);
 	if (!wmi_priv.authentication_dir_kset) {
 		ret = -ENOMEM;
-		goto fail_authentication_kset;
+		goto err_release_attributes_data;
 	}
 
 	ret = create_attributes_level_sysfs_files();
 	if (ret) {
 		pr_debug("could not create reset BIOS attribute\n");
-		goto fail_reset_bios;
+		goto err_release_attributes_data;
 	}
 
 	ret = init_bios_attributes(ENUM, DELL_WMI_BIOS_ENUMERATION_ATTRIBUTE_GUID);
 	if (ret) {
 		pr_debug("failed to populate enumeration type attributes\n");
-		goto fail_create_group;
+		goto err_release_attributes_data;
 	}
 
 	ret = init_bios_attributes(INT, DELL_WMI_BIOS_INTEGER_ATTRIBUTE_GUID);
 	if (ret) {
 		pr_debug("failed to populate integer type attributes\n");
-		goto fail_create_group;
+		goto err_release_attributes_data;
 	}
 
 	ret = init_bios_attributes(STR, DELL_WMI_BIOS_STRING_ATTRIBUTE_GUID);
 	if (ret) {
 		pr_debug("failed to populate string type attributes\n");
-		goto fail_create_group;
+		goto err_release_attributes_data;
 	}
 
 	ret = init_bios_attributes(PO, DELL_WMI_BIOS_PASSOBJ_ATTRIBUTE_GUID);
 	if (ret) {
 		pr_debug("failed to populate pass object type attributes\n");
-		goto fail_create_group;
+		goto err_release_attributes_data;
 	}
 
 	return 0;
 
-fail_create_group:
+err_release_attributes_data:
 	release_attributes_data();
 
-fail_reset_bios:
-	if (wmi_priv.authentication_dir_kset) {
-		kset_unregister(wmi_priv.authentication_dir_kset);
-		wmi_priv.authentication_dir_kset = NULL;
-	}
-
-fail_authentication_kset:
-	if (wmi_priv.main_dir_kset) {
-		kset_unregister(wmi_priv.main_dir_kset);
-		wmi_priv.main_dir_kset = NULL;
-	}
-
-fail_main_kset:
+err_destroy_classdev:
 	device_destroy(&firmware_attributes_class, MKDEV(0, 0));
 
-fail_classdev:
+err_unregister_class:
 	class_unregister(&firmware_attributes_class);
 
-fail_class:
+err_exit_bios_attr_pass_interface:
 	exit_bios_attr_pass_interface();
 
-fail_pass_interface:
+err_exit_bios_attr_set_interface:
 	exit_bios_attr_set_interface();
 
-fail_set_interface:
 	return ret;
 }
 
-- 
2.30.2

[PATCH v2 6/7] platform/x86: dell-wmi-sysman: Make sysman_init() return -ENODEV of the interfaces are not found

[Hans de Goede]

When either the attributes or the password interface is not found, then
unregister the 2 wmi drivers again and return -ENODEV from sysman_init().

Fixes: e8a60aa7404b ("platform/x86: Introduce support for Systems Management Driver over WMI for Dell Systems")
Cc: Divya Bharathi <Divya_Bharathi@dell.com>
Cc: Mario Limonciello <mario.limonciello@dell.com>
Reported-by: Alexander Naumann <alexandernaumann@gmx.de>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/platform/x86/dell/dell-wmi-sysman/sysman.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c b/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
index 99dc2f3bdf49..5dd9b29d939c 100644
--- a/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
+++ b/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
@@ -506,15 +506,17 @@ static int __init sysman_init(void)
 	}
 
 	ret = init_bios_attr_set_interface();
-	if (ret || !wmi_priv.bios_attr_wdev) {
-		pr_debug("failed to initialize set interface\n");
+	if (ret)
 		return ret;
-	}
 
 	ret = init_bios_attr_pass_interface();
-	if (ret || !wmi_priv.password_attr_wdev) {
-		pr_debug("failed to initialize pass interface\n");
+	if (ret)
 		goto err_exit_bios_attr_set_interface;
+
+	if (!wmi_priv.bios_attr_wdev || !wmi_priv.password_attr_wdev) {
+		pr_debug("failed to find set or pass interface\n");
+		ret = -ENODEV;
+		goto err_exit_bios_attr_pass_interface;
 	}
 
 	ret = class_register(&firmware_attributes_class);
-- 
2.30.2

[PATCH v2 7/7] platform/x86: dell-wmi-sysman: Cleanup create_attributes_level_sysfs_files()

[Hans de Goede]

Cleanup create_attributes_level_sysfs_files():

1. There is no need to call sysfs_remove_file() on error, sysman_init()
will already call release_attributes_data() on failure which already does
this.

2. There is no need for the pr_debug() calls sysfs_create_file() should
never fail and if it does it will already complain about the problem
itself.

Fixes: e8a60aa7404b ("platform/x86: Introduce support for Systems Management Driver over WMI for Dell Systems")
Cc: Divya Bharathi <Divya_Bharathi@dell.com>
Cc: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 .../platform/x86/dell/dell-wmi-sysman/sysman.c   | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c b/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
index 5dd9b29d939c..7410ccae650c 100644
--- a/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
+++ b/drivers/platform/x86/dell/dell-wmi-sysman/sysman.c
@@ -210,19 +210,17 @@ static struct kobj_attribute pending_reboot = __ATTR_RO(pending_reboot);
  */
 static int create_attributes_level_sysfs_files(void)
 {
-	int ret = sysfs_create_file(&wmi_priv.main_dir_kset->kobj, &reset_bios.attr);
+	int ret;
 
-	if (ret) {
-		pr_debug("could not create reset_bios file\n");
+	ret = sysfs_create_file(&wmi_priv.main_dir_kset->kobj, &reset_bios.attr);
+	if (ret)
 		return ret;
-	}
 
 	ret = sysfs_create_file(&wmi_priv.main_dir_kset->kobj, &pending_reboot.attr);
-	if (ret) {
-		pr_debug("could not create changing_pending_reboot file\n");
-		sysfs_remove_file(&wmi_priv.main_dir_kset->kobj, &reset_bios.attr);
-	}
-	return ret;
+	if (ret)
+		return ret;
+
+	return 0;
 }
 
 static ssize_t wmi_sysman_attr_show(struct kobject *kobj, struct attribute *attr,
-- 
2.30.2

Re: [PATCH v2 0/7] platform/x86: dell-wmi-sysman: Various error-handling and robustness fixes

[Hans de Goede]

Hi,

On 3/21/21 12:58 PM, Hans de Goede wrote:
> Hi All,
> 
> There have been several bug-reports about crashes related to the
> dell-wmi-sysman module:
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=1936171
> https://bugzilla.kernel.org/show_bug.cgi?id=211895
> https://bugs.archlinux.org/task/69702
> 
> Here is v2 of my series with a bunch of fixes for NULL pointer derefs,
> double-frees, etc. which fixes this.
> 
> New in v2:
> -New patch: "platform/x86: dell-wmi-sysman: Fix crash caused by calling 
> kset_unregister twice" which addresses the direct-cause of
> the crash.  Note that the crash was already fixed in v1 because
> that removed the code-path where kset_unregister ended up being
> called twice.
> 
> -Dropped: "platform/x86: dell-wmi-sysman: Make init_bios_attributes() 
> ACPI object parsing more robust". This needs more testing / discussion
> and is not necessary to fix the boot-failure which people are seeing.

I've added this series to the pdx86/review-hans and pdx86/fixes branches,
so it should show up in linux-next soon and it will also be included
in my next pull-req to Linus for 5.12.

Regards,

Hans



> Hans de Goede (7):
>   platform/x86: dell-wmi-sysman: Fix crash caused by calling
>     kset_unregister twice
>   platform/x86: dell-wmi-sysman: Fix possible NULL pointer deref on exit
>   platform/x86: dell-wmi-sysman: Make it safe to call
>     exit_foo_attributes() multiple times
>   platform/x86: dell-wmi-sysman: Fix release_attributes_data() getting
>     called twice on init_bios_attributes() failure
>   platform/x86: dell-wmi-sysman: Cleanup sysman_init() error-exit
>     handling
>   platform/x86: dell-wmi-sysman: Make sysman_init() return -ENODEV of
>     the interfaces are not found
>   platform/x86: dell-wmi-sysman: Cleanup
>     create_attributes_level_sysfs_files()
> 
>  .../dell/dell-wmi-sysman/enum-attributes.c    |  3 +
>  .../x86/dell/dell-wmi-sysman/int-attributes.c |  3 +
>  .../dell/dell-wmi-sysman/passobj-attributes.c |  3 +
>  .../dell/dell-wmi-sysman/string-attributes.c  |  3 +
>  .../x86/dell/dell-wmi-sysman/sysman.c         | 84 +++++++------------
>  5 files changed, 44 insertions(+), 52 deletions(-)
>