Comment 5 for bug 1249162

Restarting adbd on the device when in the failed state results in a partial recovery:
fginther@blackened:~$ adb devices
List of devices attached
???????????? no permissions

To get all the way back I had to also restart the adb server:
fginther@blackened:~$ adb kill-server
fginther@blackened:~$ adb start-server
* daemon not running. starting it now on port 5037 *
* daemon started successfully *
fginther@blackened:~$ adb devices
List of devices attached
01498AC41901F014 device

I collected logs from the device before restarting adbd, via 'sudo pkill -9 adbd':
dmesg.pre, syslog.pre

and after:
dmesg.post, syslog.post