sysctl: Make the header lists per directory.

Slightly enhance efficiency and clarity of the code by making the
header list per directory instead of per set.

Benchmark before:
    make-dummies 0 999 -> 0.63s
    rmmod dummy        -> 0.12s
    make-dummies 0 9999 -> 2m35s
    rmmod dummy         -> 18s

Benchmark after:
    make-dummies 0 999 -> 0.32s
    rmmod dummy        -> 0.12s
    make-dummies 0 9999 -> 1m17s
    rmmod dummy         -> 17s

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

1 files changed, 11 insertions, 17 deletions

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 160d5781638e..e971ccccac4a 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -33,12 +33,12 @@ static struct ctl_table root_table[] = {
         { }
 };
 static struct ctl_table_root sysctl_table_root = {
-        .default_set.list = LIST_HEAD_INIT(sysctl_table_root.default_set.dir.header.ctl_entry),
+        .default_set.dir.list = LIST_HEAD_INIT(sysctl_table_root.default_set.dir.list),
         .default_set.dir.header = {
                 {{.count = 1,
                   .nreg = 1,
                   .ctl_table = root_table,
-                  .ctl_entry = LIST_HEAD_INIT(sysctl_table_root.default_set.list),}},
+                  .ctl_entry = LIST_HEAD_INIT(sysctl_table_root.default_set.dir.header.ctl_entry),}},
                 .ctl_table_arg = root_table,
                 .root = &sysctl_table_root,
                 .set = &sysctl_table_root.default_set,
@@ -79,15 +79,12 @@ static int namecmp(const char *name1, int len1, const char *name2, int len2)
 static struct ctl_table *find_entry(struct ctl_table_header **phead,
         struct ctl_dir *dir, const char *name, int namelen)
 {
-        struct ctl_table_set *set = dir->header.set;
         struct ctl_table_header *head;
         struct ctl_table *entry;
 
-        list_for_each_entry(head, &set->list, ctl_entry) {
+        list_for_each_entry(head, &dir->list, ctl_entry) {
                 if (head->unregistering)
                         continue;
-                if (head->parent != dir)
-                        continue;
                 for (entry = head->ctl_table; entry->procname; entry++) {
                         const char *procname = entry->procname;
                         if (namecmp(procname, strlen(procname), name, namelen) == 0) {
@@ -133,7 +130,7 @@ static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
         err = insert_links(header);
         if (err)
                 goto fail_links;
-        list_add_tail(&header->ctl_entry, &header->set->list);
+        list_add_tail(&header->ctl_entry, &header->parent->list);
         return 0;
 fail_links:
         header->parent = NULL;
@@ -247,14 +244,12 @@ static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
 static struct ctl_table_header *next_usable_entry(struct ctl_dir *dir,
                                                   struct list_head *tmp)
 {
-        struct ctl_table_set *set = dir->header.set;
         struct ctl_table_header *head;
 
-        for (tmp = tmp->next; tmp != &set->list; tmp = tmp->next) {
+        for (tmp = tmp->next; tmp != &dir->list; tmp = tmp->next) {
                 head = list_entry(tmp, struct ctl_table_header, ctl_entry);
 
-                if (head->parent != dir ||
-                    !head->ctl_table->procname ||
+                if (!head->ctl_table->procname ||
                     !use_table(head))
                         continue;
 
@@ -270,7 +265,7 @@ static void first_entry(struct ctl_dir *dir,
         struct ctl_table *entry = NULL;
 
         spin_lock(&sysctl_lock);
-        head = next_usable_entry(dir, &dir->header.set->list);
+        head = next_usable_entry(dir, &dir->list);
         spin_unlock(&sysctl_lock);
         if (head)
                 entry = head->ctl_table;
@@ -793,6 +788,7 @@ static struct ctl_dir *new_dir(struct ctl_table_set *set,
         new_name = (char *)(table + 2);
         memcpy(new_name, name, namelen);
         new_name[namelen] = '\0';
+        INIT_LIST_HEAD(&new->list);
         table[0].procname = new_name;
         table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
         init_header(&new->header, set->dir.header.root, set, table);
@@ -917,12 +913,10 @@ static int sysctl_check_table_dups(struct ctl_dir *dir, struct ctl_table *old,
 
 static int sysctl_check_dups(struct ctl_dir *dir, struct ctl_table *table)
 {
-        struct ctl_table_set *set;
         struct ctl_table_header *head;
         int error = 0;
 
-        set = dir->header.set;
-        list_for_each_entry(head, &set->list, ctl_entry) {
+        list_for_each_entry(head, &dir->list, ctl_entry) {
                 if (head->unregistering)
                         continue;
                 if (head->parent != dir)
@@ -1494,14 +1488,14 @@ void setup_sysctl_set(struct ctl_table_set *set,
         int (*is_seen)(struct ctl_table_set *))
 {
         memset(set, sizeof(*set), 0);
-        INIT_LIST_HEAD(&set->list);
         set->is_seen = is_seen;
+        INIT_LIST_HEAD(&set->dir.list);
         init_header(&set->dir.header, root, set, root_table);
 }
 
 void retire_sysctl_set(struct ctl_table_set *set)
 {
-        WARN_ON(!list_empty(&set->list));
+        WARN_ON(!list_empty(&set->dir.list));
 }
 
 int __init proc_sys_init(void)