From cf911d4bfa5e0fd703b838406689522a41f3cb5e Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Mon, 27 Sep 2021 09:38:14 +0200 Subject: [PATCH 057/166] smp: Wake ksoftirqd on PREEMPT_RT instead do_softirq(). The softirq implementation on PREEMPT_RT does not provide do_softirq(). The other user of do_softirq() is replaced with a local_bh_disable() + enable() around the possible raise-softirq invocation. This can not be done here because migration_cpu_stop() is invoked with disabled preemption. Wake the softirq thread on PREEMPT_RT if there are any pending softirqs. Signed-off-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20210927073814.x5h6osr4dgiu44sc@linutronix.de --- kernel/smp.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) Index: linux-5.15.32-rt39/kernel/smp.c =================================================================== --- linux-5.15.32-rt39.orig/kernel/smp.c +++ linux-5.15.32-rt39/kernel/smp.c @@ -690,10 +690,20 @@ void flush_smp_call_function_from_idle(v cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->idle, CFD_SEQ_NOCPU, smp_processor_id(), CFD_SEQ_IDLE); + local_irq_save(flags); flush_smp_call_function_queue(true); - if (local_softirq_pending()) - do_softirq(); + + if (local_softirq_pending()) { + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) { + do_softirq(); + } else { + struct task_struct *ksoftirqd = this_cpu_ksoftirqd(); + + if (ksoftirqd && !task_is_running(ksoftirqd)) + wake_up_process(ksoftirqd); + } + } local_irq_restore(flags); }