Re: [PATCH v5] of/promtree: allow DT device matching by fixing 'name' brokenness

From: Andres Salomon <redacted>

Commit e2f2a93b, "of/promtree: add package-to-path support to pdt"
changed dp->name from using the 'name' property to using
package-to-path.  This fixed /proc/device-tree creation by eliminating
conflicts between names (the 'name' property provides names like
'battery', whereas package-to-path provides names like
'/foo/bar/battery@0', which we stripped to 'battery@0').  However, it
also breaks of_device_id table matching.

The fix that we _really_ wanted was to keep dp->name based upon
the name property ('battery'), but based dp->full_name upon
package-to-path ('battery@0').  This patch does just that.

This changes all users (except SPARC) of promtree to use the full
result from package-to-path for full_name, rather than stripping the
directory out.  In practice, the strings end up being exactly the
same; this change saves time, code, and memory.

SPARC continues to use the existing build_path_component() code.

v2: combine two patches and revert of_pdt_node_name to original
version v3: use dp->phandle instead of passing around node
v4: warn/bail out for non-sparc archs if pkg2path is not set
v5: split of_pdt_build_full_name into sparc & non-sparc versions
    BUG() when pkg2path doesn't work.

Signed-off-by: Andres Salomon <redacted>
Signed-off-by: Grant Likely <redacted>
---

Hi Andres,

This is what I think the patch should really look like.  The
of_pdt_node_name() stuff really doesn't make sense to keep around
because what we *really* care about is the full name, not the path
component name.  Therefore I reorganized it so SPARC continues to use
it's build_path_component() to build up the full path; but everyone
else *must* provide a working mechanism to obtain the full path; be it
an actual call to OFW pkg2path, or something else.

Please take a look at let me know what you think.

g.

 drivers/of/pdt.c |  110
++++++++++++++++++++---------------------------------- 1 files
changed, 40 insertions(+), 70 deletions(-)

diff --git a/drivers/of/pdt.c b/drivers/of/pdt.c
index 28295d0..ab54819 100644
--- a/drivers/of/pdt.c
+++ b/drivers/of/pdt.c

@@ -36,19 +36,53 @@ unsigned int of_pdt_unique_id __initdata;
 	(p)->unique_id = of_pdt_unique_id++; \
 } while (0)
 
-static inline const char *of_pdt_node_name(struct device_node *dp)
+static char * __init of_pdt_build_full_name(struct device_node *dp)
 {
-	return dp->path_component_name;
+	int len, ourlen, plen;
+	char *n;
+
+	dp->path_component_name = build_path_component(dp);
+
+	plen = strlen(dp->parent->full_name);
+	ourlen = strlen(dp->path_component_name);
+	len = ourlen + plen + 2;
+
+	n = prom_early_alloc(len);
+	strcpy(n, dp->parent->full_name);
+	if (!of_node_is_root(dp->parent)) {
+		strcpy(n + plen, "/");
+		plen++;
+	}
+	strcpy(n + plen, dp->path_component_name);
+
+	return n;
 }

 
-#else
+#else /* CONFIG_SPARC */
 
 static inline void of_pdt_incr_unique_id(void *p) { }
 static inline void irq_trans_init(struct device_node *dp) { }
 
-static inline const char *of_pdt_node_name(struct device_node *dp)
+static char * __init of_pdt_build_full_name(struct device_node *dp)
 {
-	return dp->name;
+	char *buf;
+	int len;
+
+	if (!of_pdt_prom_ops->pkg2path)
+		BUG();

+
+	if (of_pdt_prom_ops->pkg2path(dp->phandle, buf, 0, &len))
+		BUG();

+
+	buf = prom_early_alloc(len + 1);
+	if (!buf)
+		BUG();

+
+	if (of_pdt_prom_ops->pkg2path(dp->phandle, buf, len, &len)) {
+		pr_err("%s: package-to-path failed\n", __func__);
+		BUG();
+	}
+	return buf;
 }
 
 #endif /* !CONFIG_SPARC */

@@ -132,47 +166,6 @@ static char * __init

of_pdt_get_one_property(phandle node, const char *name) return buf;
 }
 
-static char * __init of_pdt_try_pkg2path(phandle node)
-{
-	char *res, *buf = NULL;
-	int len;
-
-	if (!of_pdt_prom_ops->pkg2path)
-		return NULL;
-
-	if (of_pdt_prom_ops->pkg2path(node, buf, 0, &len))
-		return NULL;
-	buf = prom_early_alloc(len + 1);
-	if (of_pdt_prom_ops->pkg2path(node, buf, len, &len)) {
-		pr_err("%s: package-to-path failed\n", __func__);
-		return NULL;
-	}
-
-	res = strrchr(buf, '/');
-	if (!res) {
-		pr_err("%s: couldn't find / in %s\n", __func__, buf);
-		return NULL;
-	}
-	return res+1;
-}
-
-/*
- * When fetching the node's name, first try using package-to-path; if
- * that fails (either because the arch hasn't supplied a PROM
callback,
- * or some other random failure), fall back to just looking at the
node's
- * 'name' property.
- */
-static char * __init of_pdt_build_name(phandle node)
-{
-	char *buf;
-
-	buf = of_pdt_try_pkg2path(node);
-	if (!buf)
-		buf = of_pdt_get_one_property(node, "name");
-
-	return buf;
-}
-
 static struct device_node * __init of_pdt_create_node(phandle node,
 						    struct
device_node *parent) {

@@ -187,7 +180,7 @@ static struct device_node * __init

of_pdt_create_node(phandle node, 
 	kref_init(&dp->kref);
 
-	dp->name = of_pdt_build_name(node);
+	dp->name = of_pdt_get_one_property(node, "name");
 	dp->type = of_pdt_get_one_property(node, "device_type");
 	dp->phandle = node;
 

@@ -198,26 +191,6 @@ static struct device_node * __init

of_pdt_create_node(phandle node, return dp;
 }
 
-static char * __init of_pdt_build_full_name(struct device_node *dp)
-{
-	int len, ourlen, plen;
-	char *n;
-
-	plen = strlen(dp->parent->full_name);
-	ourlen = strlen(of_pdt_node_name(dp));
-	len = ourlen + plen + 2;
-
-	n = prom_early_alloc(len);
-	strcpy(n, dp->parent->full_name);
-	if (!of_node_is_root(dp->parent)) {
-		strcpy(n + plen, "/");
-		plen++;
-	}
-	strcpy(n + plen, of_pdt_node_name(dp));
-
-	return n;
-}
-
 static struct device_node * __init of_pdt_build_tree(struct
device_node *parent, phandle node,
 						   struct
device_node ***nextp) @@ -240,9 +213,6 @@ static struct device_node *
__init of_pdt_build_tree(struct device_node *parent, *(*nextp) = dp;
 		*nextp = &dp->allnext;
 
-#if defined(CONFIG_SPARC)
-		dp->path_component_name = build_path_component(dp);
-#endif