livepatch: Cancel transition a safe way for immediate patches

klp_init_transition() does not set func->transition for immediate patches.
Then klp_ftrace_handler() could use the new code immediately. As a result,
it is not safe to put the livepatch module in klp_cancel_transition().

This patch reverts most of the last minute changes klp_cancel_transition().
It keeps the warning about a misuse because it still makes sense.

Fixes: 3ec24776bfd0 ("livepatch: allow removal of a disabled patch")
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index 2de09e0c4e5c2fbe9eaeee88ffbbdda0b464948e..adc0cc64aa4b6ae199e5f4a5b2af0ad59c382175 100644 (file)
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -120,31 +120,11 @@ done:
  */
 void klp_cancel_transition(void)
 {
-       struct klp_patch *patch = klp_transition_patch;
-       struct klp_object *obj;
-       struct klp_func *func;
-       bool immediate_func = false;
-
        if (WARN_ON_ONCE(klp_target_state != KLP_PATCHED))
                return;
 
        klp_target_state = KLP_UNPATCHED;
        klp_complete_transition();
-
-       /*
-        * In the enable error path, even immediate patches can be safely
-        * removed because the transition hasn't been started yet.
-        *
-        * klp_complete_transition() doesn't have a module_put() for immediate
-        * patches, so do it here.
-        */
-       klp_for_each_object(patch, obj)
-               klp_for_each_func(obj, func)
-                       if (func->immediate)
-                               immediate_func = true;
-
-       if (patch->immediate || immediate_func)
-               module_put(patch->mod);
 }
 
 /*