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Date: Fri, 13 Nov 2015 23:25:12 -0500 From: Steven Rostedt <rostedt@...dmis.org> To: <yanjiang.jin@...driver.com> Cc: <mingo@...hat.com>, <bigeasy@...utronix.de>, <peterz@...radead.org>, <linux-kernel@...r.kernel.org>, <jinyanjiang@...il.com>, <stable-rt@...r.kernel.org>, <linux-rt-users@...r.kernel.org> Subject: Re: [RT PATCH] sched: rt: fix two possible deadlocks in push_irq_work_func On Sat, 14 Nov 2015 10:53:18 +0800 <yanjiang.jin@...driver.com> wrote: > From: Yanjiang Jin <yanjiang.jin@...driver.com> > > This can only happen in RT kernel due to run_timer_softirq() calls > irq_work_tick() when CONFIG_PREEMPT_RT_FULL is enabled as below: > > static void run_timer_softirq(struct softirq_action *h) > { > ........ > if defined(CONFIG_IRQ_WORK) && defined(CONFIG_PREEMPT_RT_FULL) > irq_work_tick(); > endif > ........ > } > > Use raw_spin_{un,}lock_irq{save,restore} in push_irq_work_func() to > prevent following potentially deadlock scenario: Ug. No, the real fix is that the irq work is to be run from hard interrupt context. Moving the scheduling of high priority real-time tasks to ksoftirqd defeats the purpose. The question is, why is that irq work being run from thread context when it has the IRQ_WORK_HARD_IRQ flag set? -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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