[ndctl PATCH v4 02/10] libdaxctl: cache 'subsystem' in daxctl_ctx

[Vishal Verma <vishal.l.verma@intel.com>]

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