[PATCH] MIPS: Loongson: Use hwmon_device_register_with_groups() to register hwmon

[PATCH] MIPS: Loongson: Use hwmon_device_register_with_groups() to register hwmon

[Guenter Roeck]

Calling hwmon_device_register_with_info() with NULL dev and/or chip
information parameters is an ABI abuse and not a real conversion to
the new API. Also, the code creates sysfs attributes _after_ creating
the hwmon device, which is racy and unsupported to start with. On top
of that, the removal code tries to remove the name attribute which is
owned by the hwmon core.

Use hwmon_device_register_with_groups() to register the hwmon device
instead.

In the future, the hwmon subsystem will reject calls to
hwmon_device_register_with_info with NULL dev or chip/info parameters.
Without this patch, the hwmon device will fail to register.

Fixes: f59dc5119192 ("MIPS: Loongson: Fix boot warning about hwmon_device_register()")
Cc: Zhi Li <lizhi01@loongson.cn>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/platform/mips/cpu_hwmon.c | 127 ++++++++++--------------------
 1 file changed, 41 insertions(+), 86 deletions(-)

diff --git a/drivers/platform/mips/cpu_hwmon.c b/drivers/platform/mips/cpu_hwmon.c
index 386389ffec41..d8c5f9195f85 100644
--- a/drivers/platform/mips/cpu_hwmon.c
+++ b/drivers/platform/mips/cpu_hwmon.c
@@ -55,55 +55,6 @@ int loongson3_cpu_temp(int cpu)
 static int nr_packages;
 static struct device *cpu_hwmon_dev;
 
-static SENSOR_DEVICE_ATTR(name, 0444, NULL, NULL, 0);
-
-static struct attribute *cpu_hwmon_attributes[] = {
-	&sensor_dev_attr_name.dev_attr.attr,
-	NULL
-};
-
-/* Hwmon device attribute group */
-static struct attribute_group cpu_hwmon_attribute_group = {
-	.attrs = cpu_hwmon_attributes,
-};
-
-static ssize_t get_cpu_temp(struct device *dev,
-			struct device_attribute *attr, char *buf);
-static ssize_t cpu_temp_label(struct device *dev,
-			struct device_attribute *attr, char *buf);
-
-static SENSOR_DEVICE_ATTR(temp1_input, 0444, get_cpu_temp, NULL, 1);
-static SENSOR_DEVICE_ATTR(temp1_label, 0444, cpu_temp_label, NULL, 1);
-static SENSOR_DEVICE_ATTR(temp2_input, 0444, get_cpu_temp, NULL, 2);
-static SENSOR_DEVICE_ATTR(temp2_label, 0444, cpu_temp_label, NULL, 2);
-static SENSOR_DEVICE_ATTR(temp3_input, 0444, get_cpu_temp, NULL, 3);
-static SENSOR_DEVICE_ATTR(temp3_label, 0444, cpu_temp_label, NULL, 3);
-static SENSOR_DEVICE_ATTR(temp4_input, 0444, get_cpu_temp, NULL, 4);
-static SENSOR_DEVICE_ATTR(temp4_label, 0444, cpu_temp_label, NULL, 4);
-
-static const struct attribute *hwmon_cputemp[4][3] = {
-	{
-		&sensor_dev_attr_temp1_input.dev_attr.attr,
-		&sensor_dev_attr_temp1_label.dev_attr.attr,
-		NULL
-	},
-	{
-		&sensor_dev_attr_temp2_input.dev_attr.attr,
-		&sensor_dev_attr_temp2_label.dev_attr.attr,
-		NULL
-	},
-	{
-		&sensor_dev_attr_temp3_input.dev_attr.attr,
-		&sensor_dev_attr_temp3_label.dev_attr.attr,
-		NULL
-	},
-	{
-		&sensor_dev_attr_temp4_input.dev_attr.attr,
-		&sensor_dev_attr_temp4_label.dev_attr.attr,
-		NULL
-	}
-};
-
 static ssize_t cpu_temp_label(struct device *dev,
 			struct device_attribute *attr, char *buf)
 {
@@ -121,24 +72,47 @@ static ssize_t get_cpu_temp(struct device *dev,
 	return sprintf(buf, "%d\n", value);
 }
 
-static int create_sysfs_cputemp_files(struct kobject *kobj)
-{
-	int i, ret = 0;
-
-	for (i = 0; i < nr_packages; i++)
-		ret = sysfs_create_files(kobj, hwmon_cputemp[i]);
+static SENSOR_DEVICE_ATTR(temp1_input, 0444, get_cpu_temp, NULL, 1);
+static SENSOR_DEVICE_ATTR(temp1_label, 0444, cpu_temp_label, NULL, 1);
+static SENSOR_DEVICE_ATTR(temp2_input, 0444, get_cpu_temp, NULL, 2);
+static SENSOR_DEVICE_ATTR(temp2_label, 0444, cpu_temp_label, NULL, 2);
+static SENSOR_DEVICE_ATTR(temp3_input, 0444, get_cpu_temp, NULL, 3);
+static SENSOR_DEVICE_ATTR(temp3_label, 0444, cpu_temp_label, NULL, 3);
+static SENSOR_DEVICE_ATTR(temp4_input, 0444, get_cpu_temp, NULL, 4);
+static SENSOR_DEVICE_ATTR(temp4_label, 0444, cpu_temp_label, NULL, 4);
 
-	return ret;
-}
+static struct attribute *cpu_hwmon_attributes[] = {
+	&sensor_dev_attr_temp1_input.dev_attr.attr,
+	&sensor_dev_attr_temp1_label.dev_attr.attr,
+	&sensor_dev_attr_temp2_input.dev_attr.attr,
+	&sensor_dev_attr_temp2_label.dev_attr.attr,
+	&sensor_dev_attr_temp3_input.dev_attr.attr,
+	&sensor_dev_attr_temp3_label.dev_attr.attr,
+	&sensor_dev_attr_temp4_input.dev_attr.attr,
+	&sensor_dev_attr_temp4_label.dev_attr.attr,
+	NULL
+};
 
-static void remove_sysfs_cputemp_files(struct kobject *kobj)
+static umode_t cpu_hwmon_is_visible(struct kobject *kobj,
+				    struct attribute *attr, int i)
 {
-	int i;
+	int id = i / 2;
 
-	for (i = 0; i < nr_packages; i++)
-		sysfs_remove_files(kobj, hwmon_cputemp[i]);
+	if (id < nr_packages)
+		return attr->mode;
+	return 0;
 }
 
+static struct attribute_group cpu_hwmon_group = {
+	.attrs = cpu_hwmon_attributes,
+	.is_visible = cpu_hwmon_is_visible,
+};
+
+static const struct attribute_group *cpu_hwmon_groups[] = {
+	&cpu_hwmon_group,
+	NULL
+};
+
 #define CPU_THERMAL_THRESHOLD 90000
 static struct delayed_work thermal_work;
 
@@ -159,50 +133,31 @@ static void do_thermal_timer(struct work_struct *work)
 
 static int __init loongson_hwmon_init(void)
 {
-	int ret;
-
 	pr_info("Loongson Hwmon Enter...\n");
 
 	if (cpu_has_csr())
 		csr_temp_enable = csr_readl(LOONGSON_CSR_FEATURES) &
 				  LOONGSON_CSRF_TEMP;
 
-	cpu_hwmon_dev = hwmon_device_register_with_info(NULL, "cpu_hwmon", NULL, NULL, NULL);
-	if (IS_ERR(cpu_hwmon_dev)) {
-		ret = PTR_ERR(cpu_hwmon_dev);
-		pr_err("hwmon_device_register fail!\n");
-		goto fail_hwmon_device_register;
-	}
-
 	nr_packages = loongson_sysconf.nr_cpus /
 		loongson_sysconf.cores_per_package;
 
-	ret = create_sysfs_cputemp_files(&cpu_hwmon_dev->kobj);
-	if (ret) {
-		pr_err("fail to create cpu temperature interface!\n");
-		goto fail_create_sysfs_cputemp_files;
+	cpu_hwmon_dev = hwmon_device_register_with_groups(NULL, "cpu_hwmon",
+							  NULL, cpu_hwmon_groups);
+	if (IS_ERR(cpu_hwmon_dev)) {
+		pr_err("hwmon_device_register fail!\n");
+		return PTR_ERR(cpu_hwmon_dev);
 	}
 
 	INIT_DEFERRABLE_WORK(&thermal_work, do_thermal_timer);
 	schedule_delayed_work(&thermal_work, msecs_to_jiffies(20000));
 
-	return ret;
-
-fail_create_sysfs_cputemp_files:
-	sysfs_remove_group(&cpu_hwmon_dev->kobj,
-				&cpu_hwmon_attribute_group);
-	hwmon_device_unregister(cpu_hwmon_dev);
-
-fail_hwmon_device_register:
-	return ret;
+	return 0;
 }
 
 static void __exit loongson_hwmon_exit(void)
 {
 	cancel_delayed_work_sync(&thermal_work);
-	remove_sysfs_cputemp_files(&cpu_hwmon_dev->kobj);
-	sysfs_remove_group(&cpu_hwmon_dev->kobj,
-				&cpu_hwmon_attribute_group);
 	hwmon_device_unregister(cpu_hwmon_dev);
 }
 
-- 
2.35.1

Re: [PATCH] MIPS: Loongson: Use hwmon_device_register_with_groups() to register hwmon

[Thomas Bogendoerfer]

On Wed, May 11, 2022 at 07:56:59AM -0700, Guenter Roeck wrote:
> Calling hwmon_device_register_with_info() with NULL dev and/or chip
> information parameters is an ABI abuse and not a real conversion to
> the new API. Also, the code creates sysfs attributes _after_ creating
> the hwmon device, which is racy and unsupported to start with. On top
> of that, the removal code tries to remove the name attribute which is
> owned by the hwmon core.
> 
> Use hwmon_device_register_with_groups() to register the hwmon device
> instead.
> 
> In the future, the hwmon subsystem will reject calls to
> hwmon_device_register_with_info with NULL dev or chip/info parameters.
> Without this patch, the hwmon device will fail to register.
> 
> Fixes: f59dc5119192 ("MIPS: Loongson: Fix boot warning about hwmon_device_register()")
> Cc: Zhi Li <lizhi01@loongson.cn>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
>  drivers/platform/mips/cpu_hwmon.c | 127 ++++++++++--------------------
>  1 file changed, 41 insertions(+), 86 deletions(-)

applied to mips-next.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]