From 938aaa4f9249aa1519fd0db07fc72125de2df338 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Mon, 9 Jan 2012 17:24:30 -0800 Subject: 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 --- fs/proc/proc_sysctl.c | 28 +++++++++++++++++++--------- include/linux/sysctl.h | 1 + 2 files changed, 20 insertions(+), 9 deletions(-) diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index 15444850b3e8..13faa48c467e 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 094bc5ccf1e2..e40b8f6e5d0e 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; }; -- cgit v1.2.3