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[PATCH] sysctl: factor out sysctl_head_next from do_sysctl 

The current logic to walk through the list of sysctl table headers is slightly
painful and implement in a way it cannot be used by code outside sysctl.c

I am in the process of implementing a version of the sysctl proc support that
instead of using the proc generic non-caching monster, just uses the existing
sysctl data structure as backing store for building the dcache entries and for
doing directory reads.  To use the existing data structures however I need a
way to get at them.

[akpm@osdl.org: warning fix]
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Eric W. Biederman 2007-02-14 00:34:11 -08:00 committed by Linus Torvalds
parent 0b4d414714
commit 805b5d5e06
2 changed files with 47 additions and 17 deletions
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4
include/linux/sysctl.h
View File

@ -924,6 +924,10 @@ enum
#ifdef __KERNEL__
#include <linux/list.h>
/* For the /proc/sys support */
extern struct ctl_table_header *sysctl_head_next(struct ctl_table_header *prev);
extern void sysctl_head_finish(struct ctl_table_header *prev);
extern void sysctl_init(void);
typedef struct ctl_table ctl_table;

60
kernel/sysctl.c
View File

@ -1070,6 +1070,42 @@ static void start_unregistering(struct ctl_table_header *p)
list_del_init(&p->ctl_entry);
}
void sysctl_head_finish(struct ctl_table_header *head)
{
if (!head)
return;
spin_lock(&sysctl_lock);
unuse_table(head);
spin_unlock(&sysctl_lock);
}
struct ctl_table_header *sysctl_head_next(struct ctl_table_header *prev)
{
struct ctl_table_header *head;
struct list_head *tmp;
spin_lock(&sysctl_lock);
if (prev) {
tmp = &prev->ctl_entry;
unuse_table(prev);
goto next;
}
tmp = &root_table_header.ctl_entry;
for (;;) {
head = list_entry(tmp, struct ctl_table_header, ctl_entry);
if (!use_table(head))
goto next;
spin_unlock(&sysctl_lock);
return head;
next:
tmp = tmp->next;
if (tmp == &root_table_header.ctl_entry)
break;
}
spin_unlock(&sysctl_lock);
return NULL;
}
void __init sysctl_init(void)
{
#ifdef CONFIG_PROC_SYSCTL
@ -1081,7 +1117,7 @@ void __init sysctl_init(void)
int do_sysctl(int __user *name, int nlen, void __user *oldval, size_t __user *oldlenp,
void __user *newval, size_t newlen)
{
struct list_head *tmp;
struct ctl_table_header *head;
int error = -ENOTDIR;
if (nlen <= 0 || nlen >= CTL_MAXNAME)
@ -1091,26 +1127,16 @@ int do_sysctl(int __user *name, int nlen, void __user *oldval, size_t __user *ol
if (!oldlenp || get_user(old_len, oldlenp))
return -EFAULT;
}
spin_lock(&sysctl_lock);
tmp = &root_table_header.ctl_entry;
do {
struct ctl_table_header *head =
list_entry(tmp, struct ctl_table_header, ctl_entry);
if (!use_table(head))
continue;
spin_unlock(&sysctl_lock);
for (head = sysctl_head_next(NULL); head;
head = sysctl_head_next(head)) {
error = parse_table(name, nlen, oldval, oldlenp,
newval, newlen, head->ctl_table);
spin_lock(&sysctl_lock);
unuse_table(head);
if (error != -ENOTDIR)
if (error != -ENOTDIR) {
sysctl_head_finish(head);
break;
} while ((tmp = tmp->next) != &root_table_header.ctl_entry);
spin_unlock(&sysctl_lock);
}
}
return error;
}