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sysctl: move sysctl type to ctl_table_header

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Move the SYSCTL_TABLE_TYPE_{DEFAULT,PERMANENTLY_EMPTY} enums from
ctl_table to ctl_table_header.
Removing the mutable member is necessary to constify static instances
of struct ctl_table.

Move the initialization of the sysctl_mount_point type into
init_header() where all the other header fields are also initialized.

As a side-effect the memory usage of the sysctl core is reduced.
Each ctl_table_header instance can manage multiple ctl_table instances
and is only allocated when the table is actually registered.
This saves 8 bytes of memory per ctl_table on 64bit, 4 due to the enum
field itself and 4 due to padding.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Joel Granados <j.granados@samsung.com>
This commit is contained in:
Thomas Weißschuh
2024-03-22 18:05:57 +01:00
committed by Joel Granados
parent eb32d3adef
commit 4a7b29f650
2 changed files with 17 additions and 15 deletions
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include/linux/sysctl.h
+11 -11
View File
@@ -137,17 +137,6 @@ struct ctl_table {
void *data;
int maxlen;
umode_t mode;
/**
* 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;
@@ -188,6 +177,17 @@ struct ctl_table_header {
struct ctl_dir *parent;
struct ctl_node *node;
struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
/**
* 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;
};
struct ctl_dir {