Dell XPS 15 9550 acpi deadlock

[Andy Clayton]

Hello,

I'm seeing a blocked acpi_os_execute_deferred task on a Dell XPS 15 9550 upon thunderbolt hotplug. It seems to prevent thunderbolt from working and causes subsequent shutdown or suspend to hang. I've put together the following patch ("ACPICA: fix deadlock on recursion of entry method") that in my testing appears to fix the issue.

Thanks for looking and for any feedback. Sorry for any gaffes as this is my first kernel patch.

Andy