Re: [PATCH 3/3] hwmon: (coretemp) Fix core count limitation

[Ashok Raj]

On Mon, Nov 27, 2023 at 09:16:51PM +0800, Zhang Rui wrote:
> Currently, coretemp driver only supports 128 cores per package.
> This loses some core temperation information on systems that have more

s/temperation/temperature

> than 128 cores per package.
>  [   58.685033] coretemp coretemp.0: Adding Core 128 failed
>  [   58.692009] coretemp coretemp.0: Adding Core 129 failed
> 
> Fix the problem by using a per package list to maintain the per core
> temp_data instead of the fixed length pdata->core_data[] array.
> 
> Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx>
> ---
>  drivers/hwmon/coretemp.c | 110 ++++++++++++++++++---------------------
>  1 file changed, 52 insertions(+), 58 deletions(-)
> 
> diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c
> index cef43fedbd58..1bb1a6e4b07b 100644
> --- a/drivers/hwmon/coretemp.c
> +++ b/drivers/hwmon/coretemp.c
> @@ -39,11 +39,7 @@ static int force_tjmax;
>  module_param_named(tjmax, force_tjmax, int, 0444);
>  MODULE_PARM_DESC(tjmax, "TjMax value in degrees Celsius");
>  
> -#define PKG_SYSFS_ATTR_NO	1	/* Sysfs attribute for package temp */
> -#define BASE_SYSFS_ATTR_NO	2	/* Sysfs Base attr no for coretemp */
> -#define NUM_REAL_CORES		128	/* Number of Real cores per cpu */
>  #define CORETEMP_NAME_LENGTH	28	/* String Length of attrs */
> -#define MAX_CORE_DATA		(NUM_REAL_CORES + BASE_SYSFS_ATTR_NO)
>  
>  enum coretemp_attr_index {
>  	ATTR_LABEL,
> @@ -90,17 +86,17 @@ struct temp_data {
>  	struct attribute *attrs[TOTAL_ATTRS + 1];
>  	struct attribute_group attr_group;
>  	struct mutex update_lock;
> +	struct list_head node;
>  };
>  
>  /* Platform Data per Physical CPU */
>  struct platform_data {
>  	struct device		*hwmon_dev;
>  	u16			pkg_id;
> -	u16			cpu_map[NUM_REAL_CORES];
> -	struct ida		ida;
>  	struct cpumask		cpumask;
> -	struct temp_data	*core_data[MAX_CORE_DATA];
>  	struct device_attribute name_attr;
> +	struct mutex		core_data_lock;
> +	struct list_head	core_data_list;
>  };
>  
>  struct tjmax_pci {
> @@ -491,6 +487,23 @@ static struct temp_data *init_temp_data(unsigned int cpu, int pkg_flag)
>  	return tdata;
>  }
>  
> +static struct temp_data *get_tdata(struct platform_data *pdata, int cpu)
> +{
> +	struct temp_data *tdata;
> +
> +	mutex_lock(&pdata->core_data_lock);
> +	list_for_each_entry(tdata, &pdata->core_data_list, node) {
> +		if (cpu >= 0 && !tdata->is_pkg_data && tdata->cpu_core_id == topology_core_id(cpu))
> +			goto found;
> +		if (cpu < 0 && tdata->is_pkg_data)
> +			goto found;
> +	}
> +	tdata = NULL;

What used to be an array, is now a list? Is it possible to get the number
of cores_per_package during initialization and allocate the per-core? You
can still get them indexing from core_id and you can possibly lose the
mutex and search?

I don't know this code well enough... Just a thought.

> +found:
> +	mutex_unlock(&pdata->core_data_lock);
> +	return tdata;
> +}
> +
>  static int create_core_data(struct platform_device *pdev, unsigned int cpu,
>  			    int pkg_flag)
>  {
> @@ -498,37 +511,29 @@ static int create_core_data(struct platform_device *pdev, unsigned int cpu,
>  	struct platform_data *pdata = platform_get_drvdata(pdev);
>  	struct cpuinfo_x86 *c = &cpu_data(cpu);
>  	u32 eax, edx;
> -	int err, index, attr_no;
> +	int err, attr_no;
>  
>  	if (!housekeeping_cpu(cpu, HK_TYPE_MISC))
>  		return 0;
>  
> +	tdata = get_tdata(pdata, pkg_flag ? -1 : cpu);
> +	if (tdata)
> +		return -EEXIST;
> +
> +	tdata = init_temp_data(cpu, pkg_flag);

Is temp_data per_cpu or per_core? Wasn't sure if temp_data needs a CPU
number there along with cpu_core_id


> +	if (!tdata)
> +		return -ENOMEM;
> +
>  	/*
>  	 * Find attr number for sysfs:
>  	 * We map the attr number to core id of the CPU
>  	 * The attr number is always core id + 2
>  	 * The Pkgtemp will always show up as temp1_*, if available
>  	 */
> -	if (pkg_flag) {
> -		attr_no = PKG_SYSFS_ATTR_NO;
> -	} else {
> -		index = ida_alloc(&pdata->ida, GFP_KERNEL);
> -		if (index < 0)
> -			return index;
> -		pdata->cpu_map[index] = topology_core_id(cpu);
> -		attr_no = index + BASE_SYSFS_ATTR_NO;
> -	}
> -
> -	if (attr_no > MAX_CORE_DATA - 1) {
> -		err = -ERANGE;
> -		goto ida_free;
> -	}
> -
> -	tdata = init_temp_data(cpu, pkg_flag);
> -	if (!tdata) {
> -		err = -ENOMEM;
> -		goto ida_free;
> -	}
> +	if (pkg_flag)
> +		attr_no = 1;
> +	else
> +		attr_no = tdata->cpu_core_id + 2;
>  
>  	/* Test if we can access the status register */
>  	err = rdmsr_safe_on_cpu(cpu, tdata->status_reg, &eax, &edx);
> @@ -547,20 +552,18 @@ static int create_core_data(struct platform_device *pdev, unsigned int cpu,
>  		if (get_ttarget(tdata, &pdev->dev) >= 0)
>  			tdata->attr_size++;
>  
> -	pdata->core_data[attr_no] = tdata;
> -
>  	/* Create sysfs interfaces */
>  	err = create_core_attrs(tdata, pdata->hwmon_dev, attr_no);
>  	if (err)
>  		goto exit_free;
>  
> +	mutex_lock(&pdata->core_data_lock);
> +	list_add(&tdata->node, &pdata->core_data_list);
> +	mutex_unlock(&pdata->core_data_lock);
> +
>  	return 0;
>  exit_free:
> -	pdata->core_data[attr_no] = NULL;
>  	kfree(tdata);
> -ida_free:
> -	if (!pkg_flag)
> -		ida_free(&pdata->ida, index);
>  	return err;
>  }
>  
> @@ -571,9 +574,9 @@ coretemp_add_core(struct platform_device *pdev, unsigned int cpu, int pkg_flag)
>  		dev_err(&pdev->dev, "Adding Core %u failed\n", cpu);
>  }
>  
> -static void coretemp_remove_core(struct platform_data *pdata, int indx)
> +static void coretemp_remove_core(struct platform_data *pdata, int cpu)
>  {
> -	struct temp_data *tdata = pdata->core_data[indx];
> +	struct temp_data *tdata = get_tdata(pdata, cpu);
>  
>  	/* if we errored on add then this is already gone */
>  	if (!tdata)
> @@ -582,11 +585,11 @@ static void coretemp_remove_core(struct platform_data *pdata, int indx)
>  	/* Remove the sysfs attributes */
>  	sysfs_remove_group(&pdata->hwmon_dev->kobj, &tdata->attr_group);
>  
> -	kfree(pdata->core_data[indx]);
> -	pdata->core_data[indx] = NULL;
> +	mutex_lock(&pdata->core_data_lock);
> +	list_del(&tdata->node);
> +	mutex_unlock(&pdata->core_data_lock);
>  
> -	if (indx >= BASE_SYSFS_ATTR_NO)
> -		ida_free(&pdata->ida, indx - BASE_SYSFS_ATTR_NO);
> +	kfree(tdata);
>  }
>  
>  static int coretemp_device_add(int zoneid)
> @@ -601,7 +604,8 @@ static int coretemp_device_add(int zoneid)
>  		return -ENOMEM;
>  
>  	pdata->pkg_id = zoneid;
> -	ida_init(&pdata->ida);
> +	mutex_init(&pdata->core_data_lock);
> +	INIT_LIST_HEAD(&pdata->core_data_list);
>  
>  	pdev = platform_device_alloc(DRVNAME, zoneid);
>  	if (!pdev) {
> @@ -629,7 +633,6 @@ static void coretemp_device_remove(int zoneid)
>  	struct platform_device *pdev = zone_devices[zoneid];
>  	struct platform_data *pdata = platform_get_drvdata(pdev);
>  
> -	ida_destroy(&pdata->ida);
>  	kfree(pdata);
>  	platform_device_unregister(pdev);
>  }
> @@ -699,7 +702,7 @@ static int coretemp_cpu_offline(unsigned int cpu)
>  	struct platform_device *pdev = coretemp_get_pdev(cpu);
>  	struct platform_data *pd;
>  	struct temp_data *tdata;
> -	int i, indx = -1, target;
> +	int target;
>  
>  	/* No need to tear down any interfaces for suspend */
>  	if (cpuhp_tasks_frozen)
> @@ -710,19 +713,10 @@ static int coretemp_cpu_offline(unsigned int cpu)
>  	if (!pd->hwmon_dev)
>  		return 0;
>  
> -	for (i = 0; i < NUM_REAL_CORES; i++) {
> -		if (pd->cpu_map[i] == topology_core_id(cpu)) {
> -			indx = i + BASE_SYSFS_ATTR_NO;
> -			break;
> -		}
> -	}
> -
> -	/* Too many cores and this core is not populated, just return */
> -	if (indx < 0)
> +	tdata = get_tdata(pd, cpu);
> +	if (!tdata)
>  		return 0;
>  
> -	tdata = pd->core_data[indx];
> -
>  	cpumask_clear_cpu(cpu, &pd->cpumask);
>  
>  	/*
> @@ -732,20 +726,20 @@ static int coretemp_cpu_offline(unsigned int cpu)
>  	 */
>  	target = cpumask_any_and(&pd->cpumask, topology_sibling_cpumask(cpu));
>  	if (target >= nr_cpu_ids) {
> -		coretemp_remove_core(pd, indx);
> -	} else if (tdata && tdata->cpu == cpu) {
> +		coretemp_remove_core(pd, cpu);
> +	} else if (tdata->cpu == cpu) {
>  		mutex_lock(&tdata->update_lock);
>  		tdata->cpu = target;
>  		mutex_unlock(&tdata->update_lock);
>  	}
>  
> +	tdata = get_tdata(pd, -1);
>  	/*
>  	 * If all cores in this pkg are offline, remove the interface.
>  	 */
> -	tdata = pd->core_data[PKG_SYSFS_ATTR_NO];
>  	if (cpumask_empty(&pd->cpumask)) {
>  		if (tdata)
> -			coretemp_remove_core(pd, PKG_SYSFS_ATTR_NO);
> +			coretemp_remove_core(pd, -1);
>  		hwmon_device_unregister(pd->hwmon_dev);
>  		pd->hwmon_dev = NULL;
>  		return 0;
> -- 
> 2.34.1
>