[tip: sched/core] sched/rt: Annotate the RT balancing logic irqwork as IRQ_WORK_HARD_IRQ

[tip-bot2 for Sebastian Andrzej Siewior]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     da6ff09943491819e077b94c284bf0a6b751c9b8
Gitweb:        https://git.kernel.org/tip/da6ff09943491819e077b94c284bf0a6b751c9b8
Author:        Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
AuthorDate:    Wed, 06 Oct 2021 13:18:49 +02:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 15 Oct 2021 11:25:16 +02:00

sched/rt: Annotate the RT balancing logic irqwork as IRQ_WORK_HARD_IRQ

The push-IPI logic for RT tasks expects to be invoked from hardirq
context. One reason is that a RT task on the remote CPU would block the
softirq processing on PREEMPT_RT and so avoid pulling / balancing the RT
tasks as intended.

Annotate root_domain::rto_push_work as IRQ_WORK_HARD_IRQ.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20211006111852.1514359-2-bigeasy@xxxxxxxxxxxxx
---
 kernel/sched/topology.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index c1729f9..e812467 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -526,7 +526,7 @@ static int init_rootdomain(struct root_domain *rd)
 #ifdef HAVE_RT_PUSH_IPI
 	rd->rto_cpu = -1;
 	raw_spin_lock_init(&rd->rto_lock);
-	init_irq_work(&rd->rto_push_work, rto_push_irq_work_func);
+	rd->rto_push_work = IRQ_WORK_INIT_HARD(rto_push_irq_work_func);
 #endif
 
 	rd->visit_gen = 0;