@@ -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)
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 <lucian.grijincu@gmail.com> --- kernel/sysctl.c | 12 +++++++----- 1 files changed, 7 insertions(+), 5 deletions(-)