gFrom 9667d5ddbb1dc230653e5f8cedb778e9c562d46c Mon Sep 17 00:00:00 2001

[Xi Wang]

Instead of periodically resetting watchdogs from thread context,
this patch simply forces resched and checks rq->sched_count.
Watchdog is reset if the sched count increases. If the same thread
is picked by pick_next_task during resched, there is no context
switch.

With the new method we lose coverage on: a migration/n thread
actually gets picked and we actually context switch to the
migration/n thread. These steps are unlikely to silently fail.
The change would provide nearly the same level of protection with
less latency / jitter.

v3:
 - Removed the old method and boot option
 - Still need to check resched

v2:
 - Use sched_count instead of having sched calling into watchdog code
 - Remove the sysctl and add a boot option, which can be removed later
 - Changed the subject line

Xi Wang (1):
  sched: watchdog: Touch kernel watchdog with sched count

 include/linux/sched.h |  4 ++++
 kernel/sched/core.c   | 23 +++++++++++++++++++--
 kernel/sched/sched.h  |  6 +++++-
 kernel/watchdog.c     | 47 +++++++++++++------------------------------
 4 files changed, 44 insertions(+), 36 deletions(-)

-- 
2.29.0.rc2.309.g374f81d7ae-goog