[PATCH v3 00/22] kthread: Use kthread worker API more widely

From: Petr Mladek
Date: Wed Nov 18 2015 - 08:26:23 EST

My intention is to make it easier to manipulate and maintain kthreads.
Especially, I want to replace all the custom main cycles with a
generic one. Also I want to make the kthreads sleep in a consistent
state in a common place when there is no work.

My first attempt was with a brand new API (iterant kthread), see
http://thread.gmane.org/gmane.linux.kernel.api/11892 . But I was
directed to improve the existing kthread worker API. This is
the 3rd iteration of the new direction.

1st patch: add support to check if a timer callback is being called

2nd..12th patches: improve the existing kthread worker API

13th..18th, 20th, 22nd patches: convert several kthreads into
the kthread worker API, namely: khugepaged, ring buffer
benchmark, hung_task, kmemleak, ipmi, IB/fmr_pool,
memstick/r592, intel_powerclamp

21st, 23rd patches: do some preparation steps; they usually do
some clean up that makes sense even without the conversion.

Changes against v2:

+ used worker->lock to synchronize the operations with the work
instead of the PENDING bit as suggested by Tejun Heo; it simplified
the implementation in several ways

+ added timer_active(); used it together with del_timer_sync()
to cancel the work a less tricky way

+ removed the controversial conversion of the RCU kthreads

+ added several other examples: hung_task, kmemleak, ipmi,
IB/fmr_pool, memstick/r592, intel_powerclamp

+ the helper fixes for the ring buffer benchmark has been improved
as suggested by Steven; they already are in the Linus tree now

+ fixed a possible race between the check for existing khugepaged
worker and queuing the work

Changes against v1:

+ remove wrappers to manipulate the scheduling policy and priority

+ remove questionable wakeup_and_destroy_kthread_worker() variant

+ do not check for chained work when draining the queue

+ allocate struct kthread worker in create_kthread_work() and
use more simple checks for running worker

+ add support for delayed kthread works and use them instead
of waiting inside the works

+ rework the "unrelated" fixes for the ring buffer benchmark
as discussed in the 1st RFC; also sent separately

+ convert also the consumer in the ring buffer benchmark

I have tested this patch set against the stable Linus tree
for 4.4-rc1.

Petr Mladek (22):
timer: Allow to check when the timer callback has not finished yet
kthread/smpboot: Do not park in kthread_create_on_cpu()
kthread: Allow to call __kthread_create_on_node() with va_list args
kthread: Add create_kthread_worker*()
kthread: Add drain_kthread_worker()
kthread: Add destroy_kthread_worker()
kthread: Detect when a kthread work is used by more workers
kthread: Initial support for delayed kthread work
kthread: Allow to cancel kthread work
kthread: Allow to modify delayed kthread work
kthread: Better support freezable kthread workers
kthread: Use try_lock_kthread_work() in flush_kthread_work()
mm/huge_page: Convert khugepaged() into kthread worker API
ring_buffer: Convert benchmark kthreads into kthread worker API
hung_task: Convert hungtaskd into kthread worker API
kmemleak: Convert kmemleak kthread into kthread worker API
ipmi: Convert kipmi kthread into kthread worker API
IB/fmr_pool: Convert the cleanup thread into kthread worker API
memstick/r592: Better synchronize debug messages in r592_io kthread
memstick/r592: convert r592_io kthread into kthread worker API
thermal/intel_powerclamp: Remove duplicated code that starts the
thermal/intel_powerclamp: Convert the kthread to kthread worker API

drivers/char/ipmi/ipmi_si_intf.c | 116 ++++---
drivers/infiniband/core/fmr_pool.c | 54 ++-
drivers/memstick/host/r592.c | 61 ++--
drivers/memstick/host/r592.h | 5 +-
drivers/thermal/intel_powerclamp.c | 302 +++++++++--------
include/linux/kthread.h | 56 ++++
include/linux/timer.h | 2 +
kernel/hung_task.c | 41 ++-
kernel/kthread.c | 618 +++++++++++++++++++++++++++++++----
kernel/smpboot.c | 5 +
kernel/time/timer.c | 24 ++
kernel/trace/ring_buffer_benchmark.c | 133 ++++----
mm/huge_memory.c | 134 ++++----
mm/kmemleak.c | 86 +++--
14 files changed, 1142 insertions(+), 495 deletions(-)

CC: Catalin Marinas <catalin.marinas@xxxxxxx>
CC: linux-watchdog@xxxxxxxxxxxxxxx
CC: Corey Minyard <minyard@xxxxxxx>
CC: openipmi-developer@xxxxxxxxxxxxxxxxxxxxx
CC: Doug Ledford <dledford@xxxxxxxxxx>
CC: Sean Hefty <sean.hefty@xxxxxxxxx>
CC: Hal Rosenstock <hal.rosenstock@xxxxxxxxx>
CC: linux-rdma@xxxxxxxxxxxxxxx
CC: Maxim Levitsky <maximlevitsky@xxxxxxxxx>
CC: Zhang Rui <rui.zhang@xxxxxxxxx>
CC: Eduardo Valentin <edubezval@xxxxxxxxx>
CC: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
CC: linux-pm@xxxxxxxxxxxxxxx


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