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, 2 insertions, 0 deletions

diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 6978785bc059..6a9165d9b090 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -143,6 +143,7 @@ struct klp_object {
  * @kobj:       kobject for sysfs resources
  * @kobj_added: @kobj has been added and needs freeing
  * @enabled:    the patch is enabled (but operation may be incomplete)
+ * @forced:     was involved in a forced transition
  * @finish:     for waiting till it is safe to remove the patch module
  */
 struct klp_patch {
@@ -155,6 +156,7 @@ struct klp_patch {
         struct kobject kobj;
         bool kobj_added;
         bool enabled;
+        bool forced;
         struct completion finish;
 };