This is part of the effort to remove the empty element at the end of ctl_table structs. "child" was a deprecated elem in this struct and was being used to differentiate between two types of ctl_tables: "normal" and "permanently emtpy".
What changed?: * Replace "child" with an enumeration that will have two values: the default (0) and the permanently empty (1). The latter is left at zero so when struct ctl_table is created with kzalloc or in a local context, it will have the zero value by default. We document the new enum with kdoc. * Remove the "empty child" check from sysctl_check_table * Remove count_subheaders function as there is no longer a need to calculate how many headers there are for every child * Remove the recursive call to unregister_sysctl_table as there is no need to traverse down the child tree any longer * Add a new SYSCTL_PERM_EMPTY_DIR binary flag * Remove the last remanence of child from partport/procfs.c
Signed-off-by: Joel Granados j.granados@samsung.com --- drivers/parport/procfs.c | 1 - fs/proc/proc_sysctl.c | 81 +++++++++------------------------------- include/linux/sysctl.h | 14 ++++++- 3 files changed, 30 insertions(+), 66 deletions(-)
diff --git a/drivers/parport/procfs.c b/drivers/parport/procfs.c index 0f2d2e1ee28e..4e5b972c3e26 100644 --- a/drivers/parport/procfs.c +++ b/drivers/parport/procfs.c @@ -387,7 +387,6 @@ parport_device_sysctl_template = { .data = NULL, .maxlen = 0, .mode = 0555, - .child = NULL }, {} } diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index 07804097f997..c4ea804d862b 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -29,9 +29,8 @@ static const struct file_operations proc_sys_dir_file_operations; static const struct inode_operations proc_sys_dir_operations;
/* Support for permanently empty directories */ - struct ctl_table sysctl_mount_point[] = { - { } + {.type = SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY } };
/** @@ -48,21 +47,14 @@ struct ctl_table_header *register_sysctl_mount_point(const char *path) } EXPORT_SYMBOL(register_sysctl_mount_point);
-static bool is_empty_dir(struct ctl_table_header *head) -{ - return head->ctl_table[0].child == sysctl_mount_point; -} - -static void set_empty_dir(struct ctl_dir *dir) -{ - dir->header.ctl_table[0].child = sysctl_mount_point; -} - -static void clear_empty_dir(struct ctl_dir *dir) - -{ - dir->header.ctl_table[0].child = NULL; -} +#define sysctl_is_perm_empty_ctl_table(tptr) \ + (tptr[0].type == SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY) +#define sysctl_is_perm_empty_ctl_header(hptr) \ + (sysctl_is_perm_empty_ctl_table(hptr->ctl_table)) +#define sysctl_set_perm_empty_ctl_header(hptr) \ + (hptr->ctl_table[0].type = SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY) +#define sysctl_clear_perm_empty_ctl_header(hptr) \ + (hptr->ctl_table[0].type = SYSCTL_TABLE_TYPE_DEFAULT)
void proc_sys_poll_notify(struct ctl_table_poll *poll) { @@ -230,20 +222,22 @@ static void erase_header(struct ctl_table_header *head) static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header) { struct ctl_table *entry; + struct ctl_table_header *dir_h = &dir->header; int err;
+ /* Is this a permanently empty directory? */ - if (is_empty_dir(&dir->header)) + if (sysctl_is_perm_empty_ctl_header(dir_h)) return -EROFS;
/* Am I creating a permanently empty directory? */ - if (header->ctl_table == sysctl_mount_point) { + if (sysctl_is_perm_empty_ctl_table(header->ctl_table)) { if (!RB_EMPTY_ROOT(&dir->root)) return -EINVAL; - set_empty_dir(dir); + sysctl_set_perm_empty_ctl_header(dir_h); }
- dir->header.nreg++; + dir_h->nreg++; header->parent = dir; err = insert_links(header); if (err) @@ -259,9 +253,9 @@ static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header) put_links(header); fail_links: if (header->ctl_table == sysctl_mount_point) - clear_empty_dir(dir); + sysctl_clear_perm_empty_ctl_header(dir_h); header->parent = NULL; - drop_sysctl_table(&dir->header); + drop_sysctl_table(dir_h); return err; }
@@ -479,7 +473,7 @@ static struct inode *proc_sys_make_inode(struct super_block *sb, inode->i_mode |= S_IFDIR; inode->i_op = &proc_sys_dir_operations; inode->i_fop = &proc_sys_dir_file_operations; - if (is_empty_dir(head)) + if (sysctl_is_perm_empty_ctl_header(head)) make_empty_dir_inode(inode); }
@@ -1136,9 +1130,6 @@ static int sysctl_check_table(const char *path, struct ctl_table *table) struct ctl_table *entry; int err = 0; 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_dobool) || (entry->proc_handler == proc_dointvec) || @@ -1465,25 +1456,6 @@ void __init __register_sysctl_init(const char *path, struct ctl_table *table, kmemleak_not_leak(hdr); }
-static int count_subheaders(struct ctl_table *table) -{ - int has_files = 0; - int nr_subheaders = 0; - struct ctl_table *entry; - - /* special case: no directory and empty directory */ - if (!table || !table->procname) - return 1; - - list_for_each_table_entry(entry, table) { - if (entry->child) - nr_subheaders += count_subheaders(entry->child); - else - has_files = 1; - } - return nr_subheaders + has_files; -} - static void put_links(struct ctl_table_header *header) { struct ctl_table_set *root_set = &sysctl_table_root.default_set; @@ -1546,28 +1518,11 @@ static void drop_sysctl_table(struct ctl_table_header *header) */ void unregister_sysctl_table(struct ctl_table_header * header) { - int nr_subheaders; might_sleep();
if (header == NULL) return;
- nr_subheaders = count_subheaders(header->ctl_table_arg); - if (unlikely(nr_subheaders > 1)) { - struct ctl_table_header **subheaders; - int i; - - subheaders = (struct ctl_table_header **)(header + 1); - for (i = nr_subheaders -1; i >= 0; i--) { - struct ctl_table_header *subh = subheaders[i]; - struct ctl_table *table = subh->ctl_table_arg; - unregister_sysctl_table(subh); - kfree(table); - } - kfree(header); - return; - } - spin_lock(&sysctl_lock); drop_sysctl_table(header); spin_unlock(&sysctl_lock); diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index 653b66c762b1..59d451f455bf 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -137,7 +137,17 @@ struct ctl_table { void *data; int maxlen; umode_t mode; - struct ctl_table *child; /* Deprecated */ + /** + * enum type - Enumeration to differentiate between ctl target types + * @SYSCTL_TABLE_TYPE_DEFAULT: ctl target with no special considerations + * @SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY: Used to identify a permanently + * empty directory target to serve + * as mount point. + */ + enum { + SYSCTL_TABLE_TYPE_DEFAULT, + SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY + } type; proc_handler *proc_handler; /* Callback for text formatting */ struct ctl_table_poll *poll; void *extra1; @@ -229,7 +239,7 @@ extern int unaligned_enabled; extern int unaligned_dump_stack; extern int no_unaligned_warning;
-extern struct ctl_table sysctl_mount_point[]; +#define SYSCTL_PERM_EMPTY_DIR (1 << 0)
#else /* CONFIG_SYSCTL */