[v2 075/115] sysctl: move removal from list out of start_unregistering
From: Lucian Adrian Grijincu <hidden>
Date: 2011-05-08 22:48:41
Also in:
lkml
Subsystem:
proc sysctl, the rest · Maintainers:
Kees Cook, Joel Granados, Linus Torvalds
Later on we'll switch form a global list protected by the sysctl_lock spin lock to rwsem protected per-header lists. At that point we'll need to hold the parent header's rwlock to remove the header from the list, not the sysctl_lock spin lock. As start_unregistering is called under the sysctl_lock, we move the list removal out. Signed-off-by: Lucian Adrian Grijincu <redacted> --- kernel/sysctl.c | 12 +++++++----- 1 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 8dde087..a863b56 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c@@ -1552,11 +1552,6 @@ static void start_unregistering(struct ctl_table_header *p) /* anything non-NULL; we'll never dereference it */ p->unregistering = ERR_PTR(-EINVAL); } - /* - * do not remove from the list until nobody holds it; walking the - * list in do_sysctl() relies on that. - */ - list_del_init(&p->ctl_entry); } void sysctl_proc_inode_get(struct ctl_table_header *head)
@@ -1949,6 +1944,13 @@ void unregister_sysctl_table(struct ctl_table_header * header) spin_lock(&sysctl_lock); start_unregistering(header); + + /* after start_unregistering has finished no one holds a + * ctl_use_refs or is able to acquire one => no one is going + * to access internal fields of this object, so we can remove + * it from the list and schedule it for deletion. */ + list_del_init(&p->ctl_entry); + if (!--header->parent->ctl_header_refs) { WARN_ON(1); if (!header->parent->ctl_procfs_refs)
--
1.7.5.134.g1c08b