Jeff Epler 36b4646516 background_callback: Avoid CALLBACK_CRITICAL_BEGIN with nothing to do
CALLBACK_CRITICAL_BEGIN is heavyweight, but we can be confident we do
not have work to do as long as callback_head is NULL.

This gives back performance on nRF.
2020-07-15 09:26:47 -05:00
..
2018-08-07 14:58:57 -07:00
2020-07-06 19:16:25 +01:00
2020-07-06 19:16:25 +01:00
2020-05-15 15:36:16 -07:00
2020-01-28 17:11:25 -05:00