Commit 18d10b90 authored Feb 22, 2019 by Satya Durga Srinivasu Prabhala

hrtimer: fix issue during core isolation



During core isolation, while migrating hrtimers to one of online CPUs,
below issue is being observed due to commit 5da70160
("hrtimer: Implement support for softirq based hrtimers") which started
to enable local irqs. Fix it by moving local_bh_disable/enable calls to
hotplug path only.

[   73.488582] WARNING: CPU: 0 PID: 7 at kernel/softirq.c:106 \
					__local_bh_disable_ip+0xc4/0xd0
[   73.506182] WARNING: CPU: 0 PID: 7 at kernel/softirq.c:160 \
					__local_bh_enable_ip+0xd0/0x140
[   73.523834] kernel BUG at kernel/irq_work.c:138!
[   73.531979] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
[   73.567732] pstate: 60400005 (nZCv daif +PAN -UAO)
[   73.572663] pc : irq_work_run+0x160/0x170
[   73.576795] lr : flush_smp_call_function_queue+0x178/0x1b0
[   73.674966] Call trace:
[   73.677494]  irq_work_run+0x160/0x170
[   73.681271]  flush_smp_call_function_queue+0x178/0x1b0
[   73.686558]  generic_smp_call_function_single_interrupt+0x14/0x20
[   73.692832]  handle_IPI+0x188/0x2f8
[   73.696426]  gic_handle_irq+0x110/0x1d8
[   73.700374]  el1_irq+0xb4/0x130

Change-Id: I969171022377dc793834c4c4343e5f839f224dbe
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>

parent f5f31790

kernel/time/hrtimer.c

+7 −7

Original line number	Diff line number	Diff line
		@@ -1893,12 +1893,6 @@ static void __migrate_hrtimers(unsigned int scpu, bool remove_pinned)
		unsigned long flags;
		int i;

		/*
		* this BH disable ensures that raise_softirq_irqoff() does
		* not wakeup ksoftirqd (and acquire the pi-lock) while
		* holding the cpu_base lock
		*/
		local_bh_disable();
		local_irq_save(flags);
		old_base = &per_cpu(hrtimer_bases, scpu);
		new_base = this_cpu_ptr(&hrtimer_bases);
		@@ -1926,7 +1920,6 @@ static void __migrate_hrtimers(unsigned int scpu, bool remove_pinned)
		/* Check, if we got expired work to do */
		__hrtimer_peek_ahead_timers();
		local_irq_restore(flags);
		local_bh_enable();
		}

		int hrtimers_dead_cpu(unsigned int scpu)
		@@ -1934,7 +1927,14 @@ int hrtimers_dead_cpu(unsigned int scpu)
		BUG_ON(cpu_online(scpu));
		tick_cancel_sched_timer(scpu);

		/*
		* this BH disable ensures that raise_softirq_irqoff() does
		* not wakeup ksoftirqd (and acquire the pi-lock) while
		* holding the cpu_base lock
		*/
		local_bh_disable();
		__migrate_hrtimers(scpu, true);
		local_bh_enable();
		return 0;
		}