fs/proc: Introduce list_for_each_table_entry for proc sysctl

Use the list_for_each_table_entry macro to optimize the scenario
of traverse ctl_table. This make the code neater and easier to
understand.

Suggested-by: Davidlohr Bueso<dave@stgolabs.net>
Signed-off-by: Meng Tang <tangmeng@uniontech.com>
[updated the sysctl_check_table() hunk due to some changes upstream]
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 7d9cfc730bd4c345ccbd34f65e19c31c51fa2536..8901fe0b7e2a300b3001f89abaaf66915c738d37 100644 (file)
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -19,6 +19,9 @@
 #include <linux/kmemleak.h>
 #include "internal.h"
 
+#define list_for_each_table_entry(entry, table) \
+       for ((entry) = (table); (entry)->procname; (entry)++)
+
 static const struct dentry_operations proc_sys_dentry_operations;
 static const struct file_operations proc_sys_file_operations;
 static const struct inode_operations proc_sys_inode_operations;
@@ -215,15 +218,19 @@ static void init_header(struct ctl_table_header *head,
        INIT_HLIST_HEAD(&head->inodes);
        if (node) {
                struct ctl_table *entry;
-               for (entry = table; entry->procname; entry++, node++)
+
+               list_for_each_table_entry(entry, table) {
                        node->header = head;
+                       node++;
+               }
        }
 }
 
 static void erase_header(struct ctl_table_header *head)
 {
        struct ctl_table *entry;
-       for (entry = head->ctl_table; entry->procname; entry++)
+
+       list_for_each_table_entry(entry, head->ctl_table)
                erase_entry(head, entry);
 }
 
@@ -248,7 +255,7 @@ static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
        err = insert_links(header);
        if (err)
                goto fail_links;
-       for (entry = header->ctl_table; entry->procname; entry++) {
+       list_for_each_table_entry(entry, header->ctl_table) {
                err = insert_entry(header, entry);
                if (err)
                        goto fail;
@@ -1130,35 +1137,36 @@ static int sysctl_check_table_array(const char *path, struct ctl_table *table)
 
 static int sysctl_check_table(const char *path, struct ctl_table *table)
 {
+       struct ctl_table *entry;
        int err = 0;
-       for (; table->procname; table++) {
-               if (table->child)
-                       err |= sysctl_err(path, table, "Not a file");
-
-               if ((table->proc_handler == proc_dostring) ||
-                   (table->proc_handler == proc_dointvec) ||
-                   (table->proc_handler == proc_douintvec) ||
-                   (table->proc_handler == proc_douintvec_minmax) ||
-                   (table->proc_handler == proc_dointvec_minmax) ||
-                   (table->proc_handler == proc_dou8vec_minmax) ||
-                   (table->proc_handler == proc_dointvec_jiffies) ||
-                   (table->proc_handler == proc_dointvec_userhz_jiffies) ||
-                   (table->proc_handler == proc_dointvec_ms_jiffies) ||
-                   (table->proc_handler == proc_doulongvec_minmax) ||
-                   (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
-                       if (!table->data)
-                               err |= sysctl_err(path, table, "No data");
-                       if (!table->maxlen)
-                               err |= sysctl_err(path, table, "No maxlen");
+       list_for_each_table_entry(entry, table) {
+               if (entry->child)
+                       err |= sysctl_err(path, entry, "Not a file");
+
+               if ((entry->proc_handler == proc_dostring) ||
+                   (entry->proc_handler == proc_dointvec) ||
+                   (entry->proc_handler == proc_douintvec) ||
+                   (entry->proc_handler == proc_douintvec_minmax) ||
+                   (entry->proc_handler == proc_dointvec_minmax) ||
+                   (entry->proc_handler == proc_dou8vec_minmax) ||
+                   (entry->proc_handler == proc_dointvec_jiffies) ||
+                   (entry->proc_handler == proc_dointvec_userhz_jiffies) ||
+                   (entry->proc_handler == proc_dointvec_ms_jiffies) ||
+                   (entry->proc_handler == proc_doulongvec_minmax) ||
+                   (entry->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
+                       if (!entry->data)
+                               err |= sysctl_err(path, entry, "No data");
+                       if (!entry->maxlen)
+                               err |= sysctl_err(path, entry, "No maxlen");
                        else
-                               err |= sysctl_check_table_array(path, table);
+                               err |= sysctl_check_table_array(path, entry);
                }
-               if (!table->proc_handler)
-                       err |= sysctl_err(path, table, "No proc_handler");
+               if (!entry->proc_handler)
+                       err |= sysctl_err(path, entry, "No proc_handler");
 
-               if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
-                       err |= sysctl_err(path, table, "bogus .mode 0%o",
-                               table->mode);
+               if ((entry->mode & (S_IRUGO|S_IWUGO)) != entry->mode)
+                       err |= sysctl_err(path, entry, "bogus .mode 0%o",
+                               entry->mode);
        }
        return err;
 }
@@ -1174,7 +1182,7 @@ static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table
 
        name_bytes = 0;
        nr_entries = 0;
-       for (entry = table; entry->procname; entry++) {
+       list_for_each_table_entry(entry, table) {
                nr_entries++;
                name_bytes += strlen(entry->procname) + 1;
        }
@@ -1191,14 +1199,16 @@ static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table
        node = (struct ctl_node *)(links + 1);
        link_table = (struct ctl_table *)(node + nr_entries);
        link_name = (char *)&link_table[nr_entries + 1];
+       link = link_table;
 
-       for (link = link_table, entry = table; entry->procname; link++, entry++) {
+       list_for_each_table_entry(entry, table) {
                int len = strlen(entry->procname) + 1;
                memcpy(link_name, entry->procname, len);
                link->procname = link_name;
                link->mode = S_IFLNK|S_IRWXUGO;
                link->data = link_root;
                link_name += len;
+               link++;
        }
        init_header(links, dir->header.root, dir->header.set, node, link_table);
        links->nreg = nr_entries;
@@ -1213,7 +1223,7 @@ static bool get_links(struct ctl_dir *dir,
        struct ctl_table *entry, *link;
 
        /* Are there links available for every entry in table? */
-       for (entry = table; entry->procname; entry++) {
+       list_for_each_table_entry(entry, table) {
                const char *procname = entry->procname;
                link = find_entry(&head, dir, procname, strlen(procname));
                if (!link)
@@ -1226,7 +1236,7 @@ static bool get_links(struct ctl_dir *dir,
        }
 
        /* The checks passed.  Increase the registration count on the links */
-       for (entry = table; entry->procname; entry++) {
+       list_for_each_table_entry(entry, table) {
                const char *procname = entry->procname;
                link = find_entry(&head, dir, procname, strlen(procname));
                head->nreg++;
@@ -1329,7 +1339,7 @@ struct ctl_table_header *__register_sysctl_table(
        struct ctl_node *node;
        int nr_entries = 0;
 
-       for (entry = table; entry->procname; entry++)
+       list_for_each_table_entry(entry, table)
                nr_entries++;
 
        header = kzalloc(sizeof(struct ctl_table_header) +
@@ -1456,7 +1466,7 @@ static int count_subheaders(struct ctl_table *table)
        if (!table || !table->procname)
                return 1;
 
-       for (entry = table; entry->procname; entry++) {
+       list_for_each_table_entry(entry, table) {
                if (entry->child)
                        nr_subheaders += count_subheaders(entry->child);
                else
@@ -1475,7 +1485,7 @@ static int register_leaf_sysctl_tables(const char *path, char *pos,
        int nr_dirs = 0;
        int err = -ENOMEM;
 
-       for (entry = table; entry->procname; entry++) {
+       list_for_each_table_entry(entry, table) {
                if (entry->child)
                        nr_dirs++;
                else
@@ -1492,7 +1502,9 @@ static int register_leaf_sysctl_tables(const char *path, char *pos,
                        goto out;
 
                ctl_table_arg = files;
-               for (new = files, entry = table; entry->procname; entry++) {
+               new = files;
+
+               list_for_each_table_entry(entry, table) {
                        if (entry->child)
                                continue;
                        *new = *entry;
@@ -1516,7 +1528,7 @@ static int register_leaf_sysctl_tables(const char *path, char *pos,
        }
 
        /* Recurse into the subdirectories. */
-       for (entry = table; entry->procname; entry++) {
+       list_for_each_table_entry(entry, table) {
                char *child_pos;
 
                if (!entry->child)
@@ -1670,7 +1682,7 @@ static void put_links(struct ctl_table_header *header)
        if (IS_ERR(core_parent))
                return;
 
-       for (entry = header->ctl_table; entry->procname; entry++) {
+       list_for_each_table_entry(entry, header->ctl_table) {
                struct ctl_table_header *link_head;
                struct ctl_table *link;
                const char *name = entry->procname;