PM / devfreq: Teach lockdep about locking order
This will make it easier to catch places doing allocations that can
trigger reclaim under devfreq->lock.
Because devfreq->lock is held over various devfreq_dev_profile
callbacks, there might be some fallout if those callbacks do allocations
that can trigger reclaim, but I've looked through the various callback
implementations and don't see anything obvious. If it does trigger any
lockdep splats, those should be fixed.
Signed-off-by: Rob Clark <robdclark@chromium.org>
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 11b7740..5ce3bf9 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -817,6 +817,12 @@
}
mutex_init(&devfreq->lock);
+
+ /* Teach lockdep about lock ordering wrt. shrinker: */
+ fs_reclaim_acquire(GFP_KERNEL);
+ might_lock(&devfreq->lock);
+ fs_reclaim_release(GFP_KERNEL);
+
devfreq->dev.parent = dev;
devfreq->dev.class = devfreq_class;
devfreq->dev.release = devfreq_dev_release;
