[ndctl PATCH 2/8] libdaxctl: cache 'subsystem' in daxctl_ctx

[Vishal Verma]

The 'DAX subsystem' in effect is determined at region or device init
time, and dictates the sysfs base paths for all device/region
operations. In preparation for adding bind/unbind functionality, cache
the subsystem as determined at init time in the library context.

Cc: Dan Williams <dan.j.willi...@intel.com>
Signed-off-by: Vishal Verma <vishal.l.ve...@intel.com>
---
 daxctl/lib/libdaxctl.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/daxctl/lib/libdaxctl.c b/daxctl/lib/libdaxctl.c
index 70f896b..f8f5b8c 100644
--- a/daxctl/lib/libdaxctl.c
+++ b/daxctl/lib/libdaxctl.c
@@ -46,6 +46,7 @@ struct daxctl_ctx {
        void *userdata;
        int regions_init;
        struct list_head regions;
+       enum dax_subsystem subsys;
 };
 
 /**
@@ -96,6 +97,7 @@ DAXCTL_EXPORT int daxctl_new(struct daxctl_ctx **ctx)
        dbg(c, "log_priority=%d\n", c->ctx.log_priority);
        *ctx = c;
        list_head_init(&c->regions);
+       c->subsys = DAX_UNKNOWN;
 
        return 0;
 }
@@ -454,14 +456,18 @@ static void dax_devices_init(struct daxctl_region *region)
        for (i = 0; i < ARRAY_SIZE(dax_subsystems); i++) {
                char *region_path;
 
-               if (i == DAX_BUS)
+               if (i == DAX_BUS) {
                        region_path = region->region_path;
-               else if (i == DAX_CLASS) {
+                       if (ctx->subsys == DAX_UNKNOWN)
+                               ctx->subsys = DAX_BUS;
+               } else if (i == DAX_CLASS) {
                        if (asprintf(&region_path, "%s/dax",
                                                region->region_path) < 0) {
                                dbg(ctx, "region path alloc fail\n");
                                continue;
                        }
+                       if (ctx->subsys == DAX_UNKNOWN)
+                               ctx->subsys = DAX_CLASS;
                } else
                        continue;
                sysfs_device_parse(ctx, region_path, daxdev_fmt, region,
@@ -539,6 +545,8 @@ static void __dax_regions_init(struct daxctl_ctx *ctx, enum 
dax_subsystem subsys
                free(dev_path);
                if (!region)
                        err(ctx, "add_dax_region() for %s failed\n", 
de->d_name);
+               if (ctx->subsys == DAX_UNKNOWN)
+                       ctx->subsys = subsys;
        }
        closedir(dir);
 }
-- 
2.20.1

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