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-rw-r--r--kernel/livepatch/transition.c36
1 files changed, 34 insertions, 2 deletions
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index edcfcb8ebb2d..be5bfa533ee8 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -33,6 +33,8 @@ struct klp_patch *klp_transition_patch;
static int klp_target_state = KLP_UNDEFINED;
+static bool klp_forced = false;
+
/*
* This work can be performed periodically to finish patching or unpatching any
* "straggler" tasks which failed to transition in the first attempt.
@@ -146,9 +148,12 @@ done:
/*
* See complementary comment in __klp_enable_patch() for why we
* keep the module reference for immediate patches.
+ *
+ * klp_forced or immediate_func set implies unbounded increase of
+ * module's ref count if the module is disabled/enabled in a loop.
*/
- if (!klp_transition_patch->immediate && !immediate_func &&
- klp_target_state == KLP_UNPATCHED) {
+ if (!klp_forced && !klp_transition_patch->immediate &&
+ !immediate_func && klp_target_state == KLP_UNPATCHED) {
module_put(klp_transition_patch->mod);
}
@@ -649,3 +654,30 @@ void klp_send_signals(void)
}
read_unlock(&tasklist_lock);
}
+
+/*
+ * Drop TIF_PATCH_PENDING of all tasks on admin's request. This forces an
+ * existing transition to finish.
+ *
+ * NOTE: klp_update_patch_state(task) requires the task to be inactive or
+ * 'current'. This is not the case here and the consistency model could be
+ * broken. Administrator, who is the only one to execute the
+ * klp_force_transitions(), has to be aware of this.
+ */
+void klp_force_transition(void)
+{
+ struct task_struct *g, *task;
+ unsigned int cpu;
+
+ pr_warn("forcing remaining tasks to the patched state\n");
+
+ read_lock(&tasklist_lock);
+ for_each_process_thread(g, task)
+ klp_update_patch_state(task);
+ read_unlock(&tasklist_lock);
+
+ for_each_possible_cpu(cpu)
+ klp_update_patch_state(idle_task(cpu));
+
+ klp_forced = true;
+}