Re: [PATCH v2] powerpc/papr_scm: Make 'perf_stats' invisible if perf-stats unavailable
Thanks for looking into this patch Dan,
Dan Williams writes:
> On Fri, May 7, 2021 at 4:40 AM Vaibhav Jain wrote:
>>
>> 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')
>
> Since this has been the exposed ABI since v5.9 perhaps a note /
> analysis is needed here that the disappearance of this file will not
> break any existing scripts/tools.
>
Yes, I have added a note in patch description and also updated
Documentation/ABI/testing/sysfs-bus-papr-pmem with a note on when this
sysfs attr would be available. Thanks for this suggestion.
>> Signed-off-by: Vaibhav Jain
>> ---
>> Changelog:
>>
>> v2:
>> * Removed a redundant dev_info() from pap_scm_nvdimm_init() [ Aneesh ]
>> * Marked papr_nd_attribute_visible() as static which also fixed the
>> build warning reported by kernel build robot
>> ---
>> arch/powerpc/platforms/pseries/papr_scm.c | 35 ---
>> 1 file changed, 24 insertions(+), 11 deletions(-)
>>
>> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c
>> b/arch/powerpc/platforms/pseries/papr_scm.c
>> index e2b69cc3beaf..11e7b90a3360 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);
>>
>> +static umode_t papr_nd_attribute_visible(struct kobject *kobj,
>> +struct attribute *attr, int n)
>> +{
>> + struct device *dev = container_of(kobj, typeof(*dev), kobj);
>
> This can use the kobj_to_dev() helper.
>
Fixed in v3
>> + 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 == _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[] = {
>> _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(>region_list, _nd_regions);
>> mutex_unlock(_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(>pdev->dev, "Max perf-stat size %lu-bytes\n",
>> - p->stat_buffer_len);
>> - } else {
>> - dev_info(>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 +1184,14 @@ 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 */
>
> s/retriving/retrieving/
>
Fixed in v3.
>> + stat_size = drc_pmem_query_stats(p, NULL, 0);
>> + if (stat_size > 0) {
>> + p->stat_buffer_len = stat_size;
>> + dev_dbg(>pdev->dev, "Max perf-stat size %lu-bytes\n",
>> + p->stat_buffer_len);
>> + }
>> +
>> rc = papr_scm_nvdimm_init(p);
Re: [PATCH v2] powerpc/papr_scm: Make 'perf_stats' invisible if perf-stats unavailable
On Fri, May 7, 2021 at 4:40 AM Vaibhav Jain wrote:
>
> 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')
Since this has been the exposed ABI since v5.9 perhaps a note /
analysis is needed here that the disappearance of this file will not
break any existing scripts/tools.
> Signed-off-by: Vaibhav Jain
> ---
> Changelog:
>
> v2:
> * Removed a redundant dev_info() from pap_scm_nvdimm_init() [ Aneesh ]
> * Marked papr_nd_attribute_visible() as static which also fixed the
> build warning reported by kernel build robot
> ---
> arch/powerpc/platforms/pseries/papr_scm.c | 35 ---
> 1 file changed, 24 insertions(+), 11 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c
> b/arch/powerpc/platforms/pseries/papr_scm.c
> index e2b69cc3beaf..11e7b90a3360 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);
>
> +static umode_t papr_nd_attribute_visible(struct kobject *kobj,
> +struct attribute *attr, int n)
> +{
> + struct device *dev = container_of(kobj, typeof(*dev), kobj);
This can use the kobj_to_dev() helper.
> + 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 == _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[] = {
> _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(>region_list, _nd_regions);
> mutex_unlock(_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(>pdev->dev, "Max perf-stat size %lu-bytes\n",
> - p->stat_buffer_len);
> - } else {
> - dev_info(>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 +1184,14 @@ 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 */
s/retriving/retrieving/
> + stat_size = drc_pmem_query_stats(p, NULL, 0);
> + if (stat_size > 0) {
> + p->stat_buffer_len = stat_size;
> + dev_dbg(>pdev->dev, "Max perf-stat size %lu-bytes\n",
> + p->stat_buffer_len);
> + }
> +
> rc = papr_scm_nvdimm_init(p);
> if (rc)
> goto err2;
> --
> 2.31.1
>
After the minor fixups above you can add:
Reviewed-by: Dan Williams
...I assume this will go through the PPC tree.
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