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authorEric W. Biederman <ebiederm@xmission.com>2012-01-09 17:24:30 -0800
committerEric W. Biederman <ebiederm@xmission.com>2012-01-24 16:40:28 -0800
commit938aaa4f9249aa1519fd0db07fc72125de2df338 (patch)
treefd248564e8988e95966cd425f3f96ce7d094ae1c
parent3cc3e04636d603778d921854b84ae7bd34a349a2 (diff)
sysctl: Initial support for auto-unregistering sysctl tables.
Add nreg to ctl_table_header. When nreg drops to 0 the ctl_table_header will be unregistered. Factor out drop_sysctl_table from unregister_sysctl_table, and add the logic for decrementing nreg. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
-rw-r--r--fs/proc/proc_sysctl.c28
-rw-r--r--include/linux/sysctl.h1
2 files changed, 20 insertions, 9 deletions
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 15444850b3e..13faa48c467 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -29,8 +29,9 @@ static struct ctl_table root_table[1];
static struct ctl_table_root sysctl_table_root;
static struct ctl_table_header root_table_header = {
{{.count = 1,
- .ctl_table = root_table,
- .ctl_entry = LIST_HEAD_INIT(sysctl_table_root.default_set.list),}},
+ .nreg = 1,
+ .ctl_table = root_table,
+ .ctl_entry = LIST_HEAD_INIT(sysctl_table_root.default_set.list),}},
.root = &sysctl_table_root,
.set = &sysctl_table_root.default_set,
};
@@ -938,6 +939,7 @@ struct ctl_table_header *__register_sysctl_table(
header->unregistering = NULL;
header->root = root;
header->count = 1;
+ header->nreg = 1;
if (sysctl_check_table(path, table))
goto fail;
@@ -1192,6 +1194,20 @@ struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
}
EXPORT_SYMBOL(register_sysctl_table);
+static void drop_sysctl_table(struct ctl_table_header *header)
+{
+ if (--header->nreg)
+ return;
+
+ start_unregistering(header);
+ if (!--header->parent->count) {
+ WARN_ON(1);
+ kfree_rcu(header->parent, rcu);
+ }
+ if (!--header->count)
+ kfree_rcu(header, rcu);
+}
+
/**
* unregister_sysctl_table - unregister a sysctl table hierarchy
* @header: the header returned from register_sysctl_table
@@ -1224,13 +1240,7 @@ void unregister_sysctl_table(struct ctl_table_header * header)
}
spin_lock(&sysctl_lock);
- start_unregistering(header);
- if (!--header->parent->count) {
- WARN_ON(1);
- kfree_rcu(header->parent, rcu);
- }
- if (!--header->count)
- kfree_rcu(header, rcu);
+ drop_sysctl_table(header);
spin_unlock(&sysctl_lock);
}
EXPORT_SYMBOL(unregister_sysctl_table);
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 094bc5ccf1e..e40b8f6e5d0 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -1032,6 +1032,7 @@ struct ctl_table_header
struct list_head ctl_entry;
int used;
int count;
+ int nreg;
};
struct rcu_head rcu;
};