PM / QoS: avoid calling cancel_delayed_work_sync() during early boot

of_clk_init() ends up calling into pm_qos_update_request() very early
during boot where irq is expected to stay disabled.
pm_qos_update_request() uses cancel_delayed_work_sync() which
correctly assumes that irq is enabled on invocation and
unconditionally disables and re-enables it.

Gate cancel_delayed_work_sync() invocation with kevented_up() to avoid
enabling irq unexpectedly during early boot.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Qiao Zhou <qiaozhou@asrmicro.com>
Link: http://lkml.kernel.org/r/d2501c4c-8e7b-bea3-1b01-000b36b5dfe9@asrmicro.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/kernel/power/qos.c b/kernel/power/qos.c
index 97b0df7..168ff44 100644 (file)
--- a/kernel/power/qos.c
+++ b/kernel/power/qos.c
@@ -482,7 +482,16 @@ void pm_qos_update_request(struct pm_qos_request *req,
                return;
        }
 
-       cancel_delayed_work_sync(&req->work);
+       /*
+        * This function may be called very early during boot, for example,
+        * from of_clk_init(), where irq needs to stay disabled.
+        * cancel_delayed_work_sync() assumes that irq is enabled on
+        * invocation and re-enables it on return.  Avoid calling it until
+        * workqueue is initialized.
+        */
+       if (keventd_up())
+               cancel_delayed_work_sync(&req->work);
+
        __pm_qos_update_request(req, new_value);
 }
 EXPORT_SYMBOL_GPL(pm_qos_update_request);