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sysfs: use singly-linked list for sysfs_dirent tree

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Make sysfs_dirent use singly linked list for its tree structure.
sysfs_link_sibling() and sysfs_unlink_sibling() functions are added to
handle simpler cases.  It adds some complexity and cpu cycle overhead
but reduced memory footprint is worthwhile on big machines.

This change reduces the sizeof sysfs_dirent from 104 to 88 on 64bit
and from 60 to 52 on 32bit.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Tejun Heo 2007-06-14 03:45:18 +09:00 • committed by Greg Kroah-Hartman
parent 8619f97989
commit 0c73f18b7d
4 changed files with 112 additions and 55 deletions
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12
fs/sysfs/inode.c
View file

@ -284,8 +284,8 @@ void sysfs_drop_dentry(struct sysfs_dirent *sd)
int sysfs_hash_and_remove(struct dentry * dir, const char * name)
{
struct sysfs_dirent * sd;
struct sysfs_dirent * parent_sd;
struct sysfs_dirent **pos, *sd;
struct sysfs_dirent *parent_sd = dir->d_fsdata;
int found = 0;
if (!dir)
@ -295,13 +295,15 @@ int sysfs_hash_and_remove(struct dentry * dir, const char * name)
/* no inode means this hasn't been made visible yet */
return -ENOENT;
parent_sd = dir->d_fsdata;
mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
for (pos = &parent_sd->s_children; *pos; pos = &(*pos)->s_sibling) {
sd = *pos;
if (!sd->s_type)
continue;
if (!strcmp(sd->s_name, name)) {
list_del_init(&sd->s_sibling);
*pos = sd->s_sibling;
sd->s_sibling = NULL;
found = 1;
break;
}