libndctl/papr: Fix probe for papr-scm compatible nvdimms

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Brew: 

commit e086106b4d81a2079141c848db7695451c04e877

Author: Vaibhav Jain <vaibhav@linux.ibm.com>

Date:   Mon May 17 21:18:24 2021 +0530

    libndctl/papr: Fix probe for papr-scm compatible nvdimms

    With recent changes introduced for unification of PAPR and NFIT

    families the probe for papr-scm nvdimms is broken since they don't

    expose 'handle' or 'phys_id' sysfs attributes. These attributes are

    only exposed by NFIT and 'nvdimm_test' nvdimms. Since 'unable to read'

    these sysfs attributes is a non-recoverable error hence this prevents

    probing of 'PAPR-SCM' nvdimms and ndctl reports following error:

    $ sudo NDCTL_LOG=debug ndctl list -DH

    libndctl: ndctl_new: ctx 0x10015342c70 created

    libndctl: add_dimm: nmem1: probe failed: Operation not permitted

    libndctl: __sysfs_device_parse: nmem1: add_dev() failed

    libndctl: add_dimm: nmem0: probe failed: Operation not permitted

    libndctl: __sysfs_device_parse: nmem0: add_dev() failed

    Fixing this bug is complicated by the fact these attributes are needed

    for by the 'nvdimm_test' nvdimms which also uses the

    NVDIMM_FAMILY_PAPR. Adding a two way comparison for these two

    attributes in populate_dimm_attributes() to distinguish between

    'nvdimm_test' and papr-scm nvdimms will be clunky and make future

    updates to populate_dimm_attributes() error prone.

    So, this patch proposes to fix the issue by re-introducing

    add_papr_dimm() to probe both papr-scm and 'nvdimm_test' nvdimms. The

    'compatible' sysfs attribute associated with the PAPR device is used

    to distinguish between the two nvdimm types and in case an

    'nvdimm_test' device is detected then forward its probe to

    populate_dimm_attributes().

    families")

    Link: https://lore.kernel.org/r/20210517154824.142237-1-vaibhav@linux.ibm.com

    Fixes: daef3a386a9c("libndctl: Unify adding dimms for papr and nfit

    Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>

    Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>

diff -up ndctl-71.1/ndctl/lib/libndctl.c.orig ndctl-71.1/ndctl/lib/libndctl.c

--- ndctl-71.1/ndctl/lib/libndctl.c.orig	2022-06-06 17:16:20.703762581 -0400

+++ ndctl-71.1/ndctl/lib/libndctl.c	2022-06-06 17:17:34.932019990 -0400

@@ -1757,6 +1757,58 @@ static int populate_dimm_attributes(stru

 	return rc;

 }

+static int add_papr_dimm(struct ndctl_dimm *dimm, const char *dimm_base)

+{

+	int rc = -ENODEV;

+	char buf[SYSFS_ATTR_SIZE];

+	struct ndctl_ctx *ctx = dimm->bus->ctx;

+	char *path = calloc(1, strlen(dimm_base) + 100);

+	const char * const devname = ndctl_dimm_get_devname(dimm);

+

+	dbg(ctx, "%s: Probing of_pmem dimm at %s\n", devname, dimm_base);

+

+	if (!path)

+		return -ENOMEM;

+

+	/* Check the compatibility of the probed nvdimm */

+	sprintf(path, "%s/../of_node/compatible", dimm_base);

+	if (sysfs_read_attr(ctx, path, buf) < 0) {

+		dbg(ctx, "%s: Unable to read compatible field\n", devname);

+		rc =  -ENODEV;

+		goto out;

+	}

+

+	dbg(ctx, "%s:Compatible of_pmem = '%s'\n", devname, buf);

+

+	/* Probe for papr-scm memory */

+	if (strcmp(buf, "ibm,pmemory") == 0) {

+		/* Read the dimm flags file */

+		sprintf(path, "%s/papr/flags", dimm_base);

+		if (sysfs_read_attr(ctx, path, buf) < 0) {

+			rc = -errno;

+			err(ctx, "%s: Unable to read dimm-flags\n", devname);

+			goto out;

+		}

+

+		dbg(ctx, "%s: Adding papr-scm dimm flags:\"%s\"\n", devname, buf);

+		dimm->cmd_family = NVDIMM_FAMILY_PAPR;

+

+		/* Parse dimm flags */

+		parse_papr_flags(dimm, buf);

+

+		/* Allocate monitor mode fd */

+		dimm->health_eventfd = open(path, O_RDONLY|O_CLOEXEC);

+		rc = 0;

+

+	} else if (strcmp(buf, "nvdimm_test") == 0) {

+		/* probe via common populate_dimm_attributes() */

+		rc = populate_dimm_attributes(dimm, dimm_base, "papr");

+	}

+out:

+	free(path);

+	return rc;

+}

+

 static void *add_dimm(void *parent, int id, const char *dimm_base)

 {

 	int formats, i, rc = -ENODEV;

@@ -1848,8 +1900,9 @@ static void *add_dimm(void *parent, int

 	/* Check if the given dimm supports nfit */

 	if (ndctl_bus_has_nfit(bus)) {

 		rc = populate_dimm_attributes(dimm, dimm_base, "nfit");

-	} else if (ndctl_bus_has_of_node(bus))

-		rc = populate_dimm_attributes(dimm, dimm_base, "papr");

+	} else if (ndctl_bus_has_of_node(bus)) {

+		rc = add_papr_dimm(dimm, dimm_base);

+	}

 	if (rc == -ENODEV) {

 		/* Unprobed dimm with no family */