workqueue: Allow retrieval of current task's work struct
authorLukas Wunner <lukas@wunner.de>
Sun, 11 Feb 2018 09:38:28 +0000 (10:38 +0100)
committerLukas Wunner <lukas@wunner.de>
Fri, 16 Feb 2018 21:24:25 +0000 (22:24 +0100)
commit27d4ee03078aba88c5e07dcc4917e8d01d046f38
tree31843f798ac72fce35096eff622e4e534623a477
parent54f809cfbd6b4a43959039f5d33596ed3297ce16
workqueue: Allow retrieval of current task's work struct

Introduce a helper to retrieve the current task's work struct if it is
a workqueue worker.

This allows us to fix a long-standing deadlock in several DRM drivers
wherein the ->runtime_suspend callback waits for a specific worker to
finish and that worker in turn calls a function which waits for runtime
suspend to finish.  That function is invoked from multiple call sites
and waiting for runtime suspend to finish is the correct thing to do
except if it's executing in the context of the worker.

Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://patchwork.freedesktop.org/patch/msgid/2d8f603074131eb87e588d2b803a71765bd3a2fd.1518338788.git.lukas@wunner.de
include/linux/workqueue.h
kernel/workqueue.c