Re: [PATCH v5] ndctl: Add support for get bus and region persistence domain

[Ross Zwisler <ross.zwisler@linux.intel.com>]

On Tue, Mar 20, 2018 at 08:41:25PM -0700, Dan Williams wrote:
> On Tue, Mar 20, 2018 at 3:50 PM, Dave Jiang <dave.jiang@intel.com> wrote:
<>
> > +static int region_persistence_scan(struct ndctl_region *region)
> > +{
> > +       struct ndctl_ctx *ctx = ndctl_region_get_ctx(region);
> > +       char *pd_path;
> > +       FILE *pf;
> > +       char buf[64];
> > +       int rc = 0;
> > +       enum ndctl_persistence_domain pd = PERSISTENCE_NONE;
> > +
> > +       region->persistence_domain = PERSISTENCE_NONE;
> > +       if (asprintf(&pd_path, "%s/persistence_domain",
> > +                               region->region_path) < 0) {
> > +               rc = -errno;
> > +               err(ctx, "region persist domain path allocation failure\n");
> > +               return rc;
> > +       }
> > +
> > +       pf = fopen(pd_path, "re");
> > +       if (!pf) {
> > +               rc = -errno;
> > +               free(pd_path);
> > +               return rc;
> > +       }
> > +
> > +       do {
> > +               rc = fscanf(pf, "%s", buf);
> > +               if (rc == EOF) {
> > +                       if (ferror(pf)) {
> > +                               rc = -errno;
> > +                               goto out;
> > +                       }
> > +               } else if (rc == 1)
> > +                       pd = region_get_pd_type(buf);
> > +
> > +               if (region->persistence_domain < pd)
> > +                       region->persistence_domain = pd;
> > +       } while (rc != EOF);
> 
> I would expect sysfs_read_attr() here? I don't otherwise see a reason
> to have special case code for this attribute.

And when using sysfs_read_attr() we need to be sure to have a buffer size of
SYSFS_ATTR_SIZE instead of a hard coded 64.
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