[PATCH] ppc32/ppc64: cleanup /proc/device-tree

This cleans up the /proc/device-tree representation of the Open Firmware
device-tree on ppc and ppc64.  It does the following things:

 - Workaround an issue in some Apple device-trees where a property may
   exist with the same name as a child node of the parent.  We now
   simply "drop" the property instead of creating duplicate entries in
   /proc with random result...

 - Do not try to chop off the "@0" at the end of a node name whose unit
   address is 0.  This is not useful, inconsistent, and the code was
   buggy and didn't always work anyway.

 - Do not create symlinks for the short name and unit address parts of a
   node.  These were never really used, bloated the memory footprint of
   the device-tree with useless struct proc_dir_entry and their matching
   dentry and inode cache bloat.

This results in smaller code, smaller memory footprint, and a more
accurate view of the tree presented to userland.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 39 insertions, 87 deletions

diff --git a/arch/ppc64/kernel/pSeries_reconfig.c b/arch/ppc64/kernel/pSeries_reconfig.c
index cb5443f2e49b..dc2a69d412a2 100644
--- a/arch/ppc64/kernel/pSeries_reconfig.c
+++ b/arch/ppc64/kernel/pSeries_reconfig.c
@@ -47,14 +47,6 @@ static void remove_node_proc_entries(struct device_node *np)
                 remove_proc_entry(pp->name, np->pde);
                 pp = pp->next;
         }
-
-        /* Assuming that symlinks have the same parent directory as
-         * np->pde.
-         */
-        if (np->name_link)
-                remove_proc_entry(np->name_link->name, parent->pde);
-        if (np->addr_link)
-                remove_proc_entry(np->addr_link->name, parent->pde);
         if (np->pde)
                 remove_proc_entry(np->pde->name, parent->pde);
 }
diff --git a/fs/proc/proc_devtree.c b/fs/proc/proc_devtree.c
index 67423c696c0a..6fd57f154197 100644
--- a/fs/proc/proc_devtree.c
+++ b/fs/proc/proc_devtree.c
@@ -12,15 +12,8 @@
 #include <asm/uaccess.h>
 
 #ifndef HAVE_ARCH_DEVTREE_FIXUPS
-static inline void set_node_proc_entry(struct device_node *np, struct proc_dir_entry *de)
-{
-}
-
-static void inline set_node_name_link(struct device_node *np, struct proc_dir_entry *de)
-{
-}
-
-static void inline set_node_addr_link(struct device_node *np, struct proc_dir_entry *de)
+static inline void set_node_proc_entry(struct device_node *np,
+                                       struct proc_dir_entry *de)
 {
 }
 #endif
@@ -58,89 +51,67 @@ static int property_read_proc(char *page, char **start, off_t off,
 /*
  * Process a node, adding entries for its children and its properties.
  */
-void proc_device_tree_add_node(struct device_node *np, struct proc_dir_entry *de)
+void proc_device_tree_add_node(struct device_node *np,
+                               struct proc_dir_entry *de)
 {
         struct property *pp;
         struct proc_dir_entry *ent;
-        struct device_node *child, *sib;
-        const char *p, *at;
-        int l;
-        struct proc_dir_entry *list, **lastp, *al;
+        struct device_node *child;
+        struct proc_dir_entry *list = NULL, **lastp;
+        const char *p;
 
         set_node_proc_entry(np, de);
         lastp = &list;
-        for (pp = np->properties; pp != 0; pp = pp->next) {
-                /*
-                 * Unfortunately proc_register puts each new entry
-                 * at the beginning of the list.  So we rearrange them.
-                 */
-                ent = create_proc_read_entry(pp->name, strncmp(pp->name, "security-", 9) ?
-                                             S_IRUGO : S_IRUSR, de, property_read_proc, pp);
-                if (ent == 0)
-                        break;
-                if (!strncmp(pp->name, "security-", 9))
-                     ent->size = 0; /* don't leak number of password chars */
-                else
-                     ent->size = pp->length;
-                *lastp = ent;
-                lastp = &ent->next;
-        }
-        child = NULL;
-        while ((child = of_get_next_child(np, child))) {
+        for (child = NULL; (child = of_get_next_child(np, child));) {
                 p = strrchr(child->full_name, '/');
                 if (!p)
                         p = child->full_name;
                 else
                         ++p;
-                /* chop off '@0' if the name ends with that */
-                l = strlen(p);
-                if (l > 2 && p[l-2] == '@' && p[l-1] == '0')
-                        l -= 2;
                 ent = proc_mkdir(p, de);
                 if (ent == 0)
                         break;
                 *lastp = ent;
+                ent->next = NULL;
                 lastp = &ent->next;
                 proc_device_tree_add_node(child, ent);
-
-                /*
-                 * If we left the address part on the name, consider
-                 * adding symlinks from the name and address parts.
-                 */
-                if (p[l] != 0 || (at = strchr(p, '@')) == 0)
-                        continue;
-
+        }
+        of_node_put(child);
+        for (pp = np->properties; pp != 0; pp = pp->next) {
                 /*
-                 * If this is the first node with a given name property,
-                 * add a symlink with the name property as its name.
+                 * Yet another Apple device-tree bogosity: on some machines,
+                 * they have properties & nodes with the same name. Those
+                 * properties are quite unimportant for us though, thus we
+                 * simply "skip" them here, but we do have to check.
                  */
-                sib = NULL;
-                while ((sib = of_get_next_child(np, sib)) && sib != child)
-                        if (sib->name && strcmp(sib->name, child->name) == 0)
-                                break;
-                if (sib == child && strncmp(p, child->name, l) != 0) {
-                        al = proc_symlink(child->name, de, ent->name);
-                        if (al == 0) {
-                                of_node_put(sib);
+                for (ent = list; ent != NULL; ent = ent->next)
+                        if (!strcmp(ent->name, pp->name))
                                 break;
-                        }
-                        set_node_name_link(child, al);
-                        *lastp = al;
-                        lastp = &al->next;
+                if (ent != NULL) {
+                        printk(KERN_WARNING "device-tree: property \"%s\" name"
+                               " conflicts with node in %s\n", pp->name,
+                               np->full_name);
+                        continue;
                 }
-                of_node_put(sib);
+
                 /*
-                 * Add another directory with the @address part as its name.
+                 * Unfortunately proc_register puts each new entry
+                 * at the beginning of the list.  So we rearrange them.
                  */
-                al = proc_symlink(at, de, ent->name);
-                if (al == 0)
+                ent = create_proc_read_entry(pp->name,
+                                             strncmp(pp->name, "security-", 9)
+                                             ? S_IRUGO : S_IRUSR, de,
+                                             property_read_proc, pp);
+                if (ent == 0)
                         break;
-                set_node_addr_link(child, al);
-                *lastp = al;
-                lastp = &al->next;
+                if (!strncmp(pp->name, "security-", 9))
+                     ent->size = 0; /* don't leak number of password chars */
+                else
+                     ent->size = pp->length;
+                ent->next = NULL;
+                *lastp = ent;
+                lastp = &ent->next;
         }
-        of_node_put(child);
-        *lastp = NULL;
         de->subdir = list;
 }
 
diff --git a/include/asm-ppc64/prom.h b/include/asm-ppc64/prom.h
index 2440a2c90ae9..04b1a84f7ca3 100644
--- a/include/asm-ppc64/prom.h
+++ b/include/asm-ppc64/prom.h
@@ -147,9 +147,7 @@ struct device_node {
         struct  device_node *sibling;
         struct  device_node *next;      /* next device of same type */
         struct  device_node *allnext;   /* next in list of all nodes */
-        struct  proc_dir_entry *pde;       /* this node's proc directory */
-        struct  proc_dir_entry *name_link; /* name symlink */
-        struct  proc_dir_entry *addr_link; /* addr symlink */
+        struct  proc_dir_entry *pde;    /* this node's proc directory */
         struct  kref kref;
         unsigned long _flags;
 };
@@ -174,15 +172,6 @@ static inline void set_node_proc_entry(struct device_node *dn, struct proc_dir_e
         dn->pde = de;
 }
 
-static void inline set_node_name_link(struct device_node *dn, struct proc_dir_entry *de)
-{
-        dn->name_link = de;
-}
-
-static void inline set_node_addr_link(struct device_node *dn, struct proc_dir_entry *de)
-{
-        dn->addr_link = de;
-}
 
 /* OBSOLETE: Old stlye node lookup */
 extern struct device_node *find_devices(const char *name);