"Aneesh Kumar K.V" <aneesh.ku...@linux.ibm.com> writes:
> Vaibhav Jain <vaib...@linux.ibm.com> writes:
>
>> In case performance stats for an nvdimm are not available, reading the
>> 'perf_stats' sysfs file returns an -ENOENT error. A better approach is
>> to make the 'perf_stats' file entirely invisible to indicate that
>> performance stats for an nvdimm are unavailable.
>>
>> So this patch updates 'papr_nd_attribute_group' to add a 'is_visible'
>> callback implemented as newly introduced 'papr_nd_attribute_visible()'
>> that returns an appropriate mode in case performance stats aren't
>> supported in a given nvdimm.
>>
>> Also the initialization of 'papr_scm_priv.stat_buffer_len' is moved
>> from papr_scm_nvdimm_init() to papr_scm_probe() so that it value is
>> available when 'papr_nd_attribute_visible()' is called during nvdimm
>> initialization.
>>
>> Fixes: 2d02bf835e57('powerpc/papr_scm: Fetch nvdimm performance stats from
>> PHYP')
>> Signed-off-by: Vaibhav Jain <vaib...@linux.ibm.com>
>> ---
>> arch/powerpc/platforms/pseries/papr_scm.c | 37 ++++++++++++++++-------
>> 1 file changed, 26 insertions(+), 11 deletions(-)
>>
>> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c
>> b/arch/powerpc/platforms/pseries/papr_scm.c
>> index 12f1513f0fca..90f0af8fefe8 100644
>> --- a/arch/powerpc/platforms/pseries/papr_scm.c
>> +++ b/arch/powerpc/platforms/pseries/papr_scm.c
>> @@ -907,6 +907,20 @@ static ssize_t flags_show(struct device *dev,
>> }
>> DEVICE_ATTR_RO(flags);
>>
>> +umode_t papr_nd_attribute_visible(struct kobject *kobj, struct attribute
>> *attr,
>> + int n)
>> +{
>> + struct device *dev = container_of(kobj, typeof(*dev), kobj);
>> + struct nvdimm *nvdimm = to_nvdimm(dev);
>> + struct papr_scm_priv *p = nvdimm_provider_data(nvdimm);
>> +
>> + /* For if perf-stats not available remove perf_stats sysfs */
>> + if (attr == &dev_attr_perf_stats.attr && p->stat_buffer_len == 0)
>> + return 0;
>> +
>> + return attr->mode;
>> +}
>> +
>> /* papr_scm specific dimm attributes */
>> static struct attribute *papr_nd_attributes[] = {
>> &dev_attr_flags.attr,
>> @@ -916,6 +930,7 @@ static struct attribute *papr_nd_attributes[] = {
>>
>> static struct attribute_group papr_nd_attribute_group = {
>> .name = "papr",
>> + .is_visible = papr_nd_attribute_visible,
>> .attrs = papr_nd_attributes,
>> };
>>
>> @@ -931,7 +946,6 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
>> struct nd_region_desc ndr_desc;
>> unsigned long dimm_flags;
>> int target_nid, online_nid;
>> - ssize_t stat_size;
>>
>> p->bus_desc.ndctl = papr_scm_ndctl;
>> p->bus_desc.module = THIS_MODULE;
>> @@ -1016,16 +1030,6 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv
>> *p)
>> list_add_tail(&p->region_list, &papr_nd_regions);
>> mutex_unlock(&papr_ndr_lock);
>>
>> - /* Try retriving the stat buffer and see if its supported */
>> - stat_size = drc_pmem_query_stats(p, NULL, 0);
>> - if (stat_size > 0) {
>> - p->stat_buffer_len = stat_size;
>> - dev_dbg(&p->pdev->dev, "Max perf-stat size %lu-bytes\n",
>> - p->stat_buffer_len);
>> - } else {
>> - dev_info(&p->pdev->dev, "Dimm performance stats unavailable\n");
>> - }
>> -
>> return 0;
>>
>> err: nvdimm_bus_unregister(p->bus);
>> @@ -1102,6 +1106,7 @@ static int papr_scm_probe(struct platform_device *pdev)
>> u64 blocks, block_size;
>> struct papr_scm_priv *p;
>> const char *uuid_str;
>> + ssize_t stat_size;
>> u64 uuid[2];
>> int rc;
>>
>> @@ -1179,6 +1184,16 @@ static int papr_scm_probe(struct platform_device
>> *pdev)
>> p->res.name = pdev->name;
>> p->res.flags = IORESOURCE_MEM;
>>
>> + /* Try retriving the stat buffer and see if its supported */
>> + stat_size = drc_pmem_query_stats(p, NULL, 0);
>> + if (stat_size > 0) {
>> + p->stat_buffer_len = stat_size;
>> + dev_dbg(&p->pdev->dev, "Max perf-stat size %lu-bytes\n",
>> + p->stat_buffer_len);
>> + } else {
>> + dev_info(&p->pdev->dev, "Dimm performance stats unavailable\n");
>> + }
>
> With this patch
> https://lore.kernel.org/linuxppc-dev/20210505191606.51666-1-vaib...@linux.ibm.com
> We are adding details of whyy performance stat query hcall failed. Do we
> need to print again here? Are we being more verbose here?
>
Yes agree this looks more verbose with the other patch you mentioned. I
have sent out a v2 of this patch with this dev_info removed.
> -aneesh
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--
Cheers
~ Vaibhav
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