Re: [PATCH 2/3] nfit, libnvdimm: allow an ARS rescan to be triggered on demand

On Mon, Jul 18, 2016 at 5:44 PM, Vishal Verma <vishal.l.verma(a)intel.com&gt; wrote: > Normally, an ARS (Address Range Scrub) only happens at > boot/initialization time. There can however arise situations where a > bus-wide rescan is needed - notably, in the case of discovering a latent > media error, we should do a full rescan to figure out what other sectors > are bad, and thus potentially avoid triggering an mce on them in the > future. Also provide a sysfs trigger to start a bus-wide rescan. > > Cc: Dan Williams <dan.j.williams(a)intel.com&gt; > Cc: Rafael J. Wysocki <rafael.j.wysocki(a)intel.com&gt; > Cc: <linux-acpi(a)vger.kernel.org&gt; > Cc: <linux-nvdimm(a)lists.01.org&gt; > Signed-off-by: Vishal Verma <vishal.l.verma(a)intel.com&gt; > --- > drivers/acpi/nfit.c | 36 ++++++++++++++++++++++++++++++++---- > drivers/acpi/nfit.h | 1 + > drivers/nvdimm/core.c | 17 +++++++++++++++++ > include/linux/libnvdimm.h | 1 + > 4 files changed, 51 insertions(+), 4 deletions(-) > > diff --git a/drivers/acpi/nfit.c b/drivers/acpi/nfit.c > index ac6ddcc0..def9505 100644 > --- a/drivers/acpi/nfit.c > +++ b/drivers/acpi/nfit.c > @@ -2138,8 +2138,9 @@ static void acpi_nfit_async_scrub(struct acpi_nfit_desc *acpi_desc, > unsigned int tmo = scrub_timeout; > int rc; > > - if (nfit_spa->ars_done || !nfit_spa->nd_region) > - return; > + if (!nfit_spa->ars_rescan) > + if (nfit_spa->ars_done || !nfit_spa->nd_region) > + return; Do we need a new flag? Why not just clear ->ars_done?

> > rc = ars_start(acpi_desc, nfit_spa); > /* > @@ -2227,7 +2228,9 @@ static void acpi_nfit_scrub(struct work_struct *work) > * firmware initiated scrubs to complete and then we go search for the > * affected spa regions to mark them scanned. In the second phase we > * initiate a directed scrub for every range that was not scrubbed in > - * phase 1. > + * phase 1. If we're called for a 'rescan', we harmlessly pass through > + * the first phase, but really only care about running phase 2, where > + * regions can be notified of new poison. > */ I don't think we need to distinguish the initial scan case from the re-scan case in acpi_nfit_scrub(). Whether it's a scan or a re-scan doesn't matter to acpi_nfit_scrub().

> > /* process platform firmware initiated scrubs */ > @@ -2336,8 +2339,10 @@ static void acpi_nfit_scrub(struct work_struct *work) > acpi_nfit_register_region(acpi_desc, nfit_spa); > } > > - list_for_each_entry(nfit_spa, &acpi_desc->spas, list) > + list_for_each_entry(nfit_spa, &acpi_desc->spas, list) { > acpi_nfit_async_scrub(acpi_desc, nfit_spa); > + nfit_spa->ars_rescan = 0; > + } > mutex_unlock(&acpi_desc->init_mutex); > } > > @@ -2495,6 +2500,28 @@ static int acpi_nfit_clear_to_send(struct nvdimm_bus_descriptor *nd_desc, > return 0; > } > > +static int acpi_nfit_ars_rescan(struct nvdimm_bus_descriptor *nd_desc) > +{ > + struct acpi_nfit_desc *acpi_desc = to_acpi_nfit_desc(nd_desc); > + struct device *dev = acpi_desc->dev; > + struct nfit_spa *nfit_spa; > + > + if (work_busy(&acpi_desc->work)) > + return -EBUSY; How does userspace figure out when the queue is not busy? See below in the notes about the ars_rescan attribute. > + > + list_for_each_entry(nfit_spa, &acpi_desc->spas, list) { > + struct acpi_nfit_system_address *spa = nfit_spa->spa; > + > + if (nfit_spa_type(spa) != NFIT_SPA_PM) > + continue; > + > + nfit_spa->ars_rescan = 1; > + } > + queue_work(nfit_wq, &acpi_desc->work); > + dev_info(dev, "%s: ars_rescan triggered\n", __func__); > + return 0; > +} > + > void acpi_nfit_desc_init(struct acpi_nfit_desc *acpi_desc, struct device *dev) > { > struct nvdimm_bus_descriptor *nd_desc; > @@ -2507,6 +2534,7 @@ void acpi_nfit_desc_init(struct acpi_nfit_desc *acpi_desc, struct device *dev) > nd_desc->ndctl = acpi_nfit_ctl; > nd_desc->flush_probe = acpi_nfit_flush_probe; > nd_desc->clear_to_send = acpi_nfit_clear_to_send; > + nd_desc->ars_rescan = acpi_nfit_ars_rescan; > nd_desc->attr_groups = acpi_nfit_attribute_groups; > > INIT_LIST_HEAD(&acpi_desc->spa_maps); > diff --git a/drivers/acpi/nfit.h b/drivers/acpi/nfit.h > index 02b9ea1..db95c5d 100644 > --- a/drivers/acpi/nfit.h > +++ b/drivers/acpi/nfit.h > @@ -78,6 +78,7 @@ struct nfit_spa { > struct list_head list; > struct nd_region *nd_region; > unsigned int ars_done:1; > + unsigned int ars_rescan:1; > u32 clear_err_unit; > u32 max_ars; > }; > diff --git a/drivers/nvdimm/core.c b/drivers/nvdimm/core.c > index be89764..54f6fd5 100644 > --- a/drivers/nvdimm/core.c > +++ b/drivers/nvdimm/core.c > @@ -313,10 +313,27 @@ static ssize_t wait_probe_show(struct device *dev, > } > static DEVICE_ATTR_RO(wait_probe); > > +static ssize_t ars_rescan_store(struct device *dev, > + struct device_attribute *attr, const char *buf, size_t size) > +{ > + struct nvdimm_bus *nvdimm_bus = to_nvdimm_bus(dev); > + struct nvdimm_bus_descriptor *nd_desc = nvdimm_bus->nd_desc; > + int rc; > + > + if (nd_desc->ars_rescan) { > + rc = nd_desc->ars_rescan(nd_desc); > + if (rc) > + return rc; > + } > + return size; > +} > +static DEVICE_ATTR_WO(ars_rescan); A few notes: 1/ ARS is unique to the nfit driver so let's make this nfit specific, i.e. add it to acpi_nfit_attribute_group. 2/ Let's just call the attribute scrub and not distinguish it as "re-" 3/ Userspace may want to know when scanning is complete so let's make this attribute read/write and on read return a count of the number of completed scans since the driver was loaded. For notification of last completion use sysfs_notify_dirent_safe() to make this scrub attribute select()/poll() capable.

> + > static struct attribute *nvdimm_bus_attributes[] = { > &dev_attr_commands.attr, > &dev_attr_wait_probe.attr, > &dev_attr_provider.attr, > + &dev_attr_ars_rescan.attr, > NULL, > }; > > diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h > index 0c3c30c..1c6867a 100644 > --- a/include/linux/libnvdimm.h > +++ b/include/linux/libnvdimm.h > @@ -74,6 +74,7 @@ struct nvdimm_bus_descriptor { > int (*flush_probe)(struct nvdimm_bus_descriptor *nd_desc); > int (*clear_to_send)(struct nvdimm_bus_descriptor *nd_desc, > struct nvdimm *nvdimm, unsigned int cmd); > + int (*ars_rescan)(struct nvdimm_bus_descriptor *nd_desc); > }; > > struct nd_cmd_desc { > -- > 2.7.4 >