livepatch: Don't block the removal of patches loaded after a forced transition

module_put() is currently never called in klp_complete_transition() when
klp_force is set. As a result, we might keep the reference count even when
klp_enable_patch() fails and klp_cancel_transition() is called.

This might give the impression that a module might get blocked in some
strange init state. Fortunately, it is not the case. The reference count
is ignored when mod->init fails and erroneous modules are always removed.

Anyway, this might be confusing. Instead, this patch moves
the global klp_forced flag into struct klp_patch. As a result,
we block only modules that might still be in use after a forced
transition. Newly loaded livepatches might be eventually completely
removed later.

It is not a big deal. But the code is at least consistent with
the reality.

Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 3 insertions, 1 deletions

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 6f0d9095f662..e77c5017ae0c 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -45,7 +45,8 @@
  */
 DEFINE_MUTEX(klp_mutex);
 
-static LIST_HEAD(klp_patches);
+/* Registered patches */
+LIST_HEAD(klp_patches);
 
 static struct kobject *klp_root_kobj;
 
@@ -659,6 +660,7 @@ static int klp_init_patch_early(struct klp_patch *patch)
         INIT_LIST_HEAD(&patch->list);
         patch->kobj_added = false;
         patch->enabled = false;
+        patch->forced = false;
         init_completion(&patch->finish);
 
         klp_for_each_object(patch, obj) {