Re: [PATCH] powerpc/papr_scm: Make 'perf_stats' invisible if perf-stats unavailable

Vaibhav Jain <vaibhav(a)linux.ibm.com&gt; 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 <vaibhav(a)linux.ibm.com&gt; > --- > 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-vaibhav@linux... We are adding details of whyy performance stat query hcall failed. Do we need to print again here? Are we being more verbose here?

-aneesh _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm(a)lists.01.org To unsubscribe send an email to linux-nvdimm-leave(a)lists.01.org