Commit 2f2665c1 authored by Joel Granados's avatar Joel Granados Committed by Luis Chamberlain
Browse files

sysctl: replace child with an enumeration 



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: default avatarJoel Granados <j.granados@samsung.com>
Signed-off-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
parent 94a64905

drivers/parport/procfs.c

+0 −1
Original line number Diff line number Diff line
@@ -387,7 +387,6 @@ parport_device_sysctl_template = { 
			.data		= NULL,

			.maxlen		= 0,

			.mode		= 0555,

			.child		= NULL

		},

		{}

	}

fs/proc/proc_sysctl.c

+18 −63
Original line number Diff line number Diff line
@@ -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);

include/linux/sysctl.h

+12 −2
Original line number Diff line number Diff line
@@ -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 */