Commit b0864c12 authored Jun 19, 2017 by Channagoud Kadabi Committed by Rishabh Bhatnagar Jul 16, 2018

kernel: cpu: Handle hotplug failure for state CPUHP_AP_IDLE_DEAD



Once the tear down hotplug handler is run cpu is dead and enters
into CPUHP_AP_IDLE_DEAD state. Any callbacks that fail in the state
machine with state < CPUHP_AP_IDLE must be treated as fatal. As this
could result into timer not being migrated away from dead cpu and run
into issues like work queue lock ups, sched_clock timer wrapping to
zero as sched_clock_pll which is in the hrtimer base of cpu being
hotplugged does not get migrated.

Change-Id: I214c329f5a342d676cc26f57dba453d4a2cbe1a6
Signed-off-by: Channagoud Kadabi <ckadabi@codeaurora.org>
Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>

parent be37633b

kernel/cpu.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -837,6 +837,7 @@ static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,

		for (; st->state > target; st->state--) {
		ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);
		BUG_ON(ret && st->state < CPUHP_AP_IDLE_DEAD);
		if (ret) {
		st->target = prev_state;
		undo_cpu_down(cpu, st);