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@xxxxxxxxxxxxxx>
---
fs/proc/proc_sysctl.c | 10 ++++++----
include/linux/sysctl.h | 22 +++++++++++-----------
2 files changed, 17 insertions(+), 15 deletions(-)
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 2f4d4329d83d..fde7a2f773f0 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -31,7 +31,7 @@ static const struct inode_operations proc_sys_dir_operations;
/* Support for permanently empty directories */
static struct ctl_table sysctl_mount_point[] = {
- {.type = SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY }
+ { }
};
/**
@@ -49,11 +49,11 @@ struct ctl_table_header *register_sysctl_mount_point(const char *path)
EXPORT_SYMBOL(register_sysctl_mount_point);
#define sysctl_is_perm_empty_ctl_header(hptr) \
- (hptr->ctl_table[0].type == SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY)
+ (hptr->type == SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY)
#define sysctl_set_perm_empty_ctl_header(hptr) \
- (hptr->ctl_table[0].type = SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY)
+ (hptr->type = SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY)
#define sysctl_clear_perm_empty_ctl_header(hptr) \
- (hptr->ctl_table[0].type = SYSCTL_TABLE_TYPE_DEFAULT)
+ (hptr->type = SYSCTL_TABLE_TYPE_DEFAULT)
void proc_sys_poll_notify(struct ctl_table_poll *poll)
{
@@ -208,6 +208,8 @@ static void init_header(struct ctl_table_header *head,
node++;
}
}
+ if (table == sysctl_mount_point)
+ sysctl_set_perm_empty_ctl_header(head);
}
static void erase_header(struct ctl_table_header *head)
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index ee7d33b89e9e..c87f73c06cb9 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -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 {
--
2.44.0
