diff options
Diffstat (limited to 'kernel/sysctl.c')
-rw-r--r-- | kernel/sysctl.c | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 60d9357..c9a0af8 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1680,6 +1680,52 @@ static __init int sysctl_init(void) core_initcall(sysctl_init); +static int is_branch_in(struct ctl_table *branch, struct ctl_table *table) +{ + struct ctl_table *p; + const char *s = branch->procname; + + /* branch should have named subdirectory as its first element */ + if (!s || !branch->child) + return 0; + + /* ... and nothing else */ + if (branch[1].procname || branch[1].ctl_name) + return 0; + + /* table should contain subdirectory with the same name */ + for (p = table; p->procname || p->ctl_name; p++) { + if (!p->child) + continue; + if (p->procname && strcmp(p->procname, s) == 0) + return 1; + } + return 0; +} + +/* see if attaching q to p would be an improvement */ +static void try_attach(struct ctl_table_header *p, struct ctl_table_header *q) +{ + struct ctl_table *to = p->ctl_table, *by = q->ctl_table; + int is_better = 0; + int not_in_parent = !p->attached_by; + + while (is_branch_in(by, to)) { + if (by == q->attached_by) + is_better = 1; + if (to == p->attached_by) + not_in_parent = 1; + by = by->child; + to = to->child; + } + + if (is_better && not_in_parent) { + q->attached_by = by; + q->attached_to = to; + q->parent = p; + } +} + /** * __register_sysctl_paths - register a sysctl hierarchy * @root: List of sysctl headers to register on @@ -1759,6 +1805,7 @@ struct ctl_table_header *__register_sysctl_paths( struct ctl_table_header *header; struct ctl_table *new, **prevp; unsigned int n, npath; + struct ctl_table_set *set; /* Count the path components */ for (npath = 0; path[npath].ctl_name || path[npath].procname; ++npath) @@ -1809,6 +1856,18 @@ struct ctl_table_header *__register_sysctl_paths( #endif spin_lock(&sysctl_lock); header->set = lookup_header_set(root, namespaces); + header->attached_by = header->ctl_table; + header->attached_to = root_table; + header->parent = &root_table_header; + for (set = header->set; set; set = set->parent) { + struct ctl_table_header *p; + list_for_each_entry(p, &set->list, ctl_entry) { + if (p->unregistering) + continue; + try_attach(p, header); + } + } + header->parent->count++; list_add_tail(&header->ctl_entry, &header->set->list); spin_unlock(&sysctl_lock); @@ -1864,6 +1923,10 @@ void unregister_sysctl_table(struct ctl_table_header * header) spin_lock(&sysctl_lock); start_unregistering(header); + if (!--header->parent->count) { + WARN_ON(1); + kfree(header->parent); + } if (!--header->count) kfree(header); spin_unlock(&sysctl_lock); |