Messages in this thread | | | Subject | Re: [RESEND 1/1] gic: its: Make sure a LPI is discarded before free. | From | Marc Zyngier <> | Date | Wed, 9 Jan 2019 09:52:08 +0000 |
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On 09/01/2019 09:29, Zhao, Yuanyuan wrote: > Hi Marc: > > Thank you for your reply. > > As you said, APIs such as free_irq will deactivate irq > before free it. But deactivation is not forced by every API, > for example irq_dispose_mapping. So I think it's better to check > that irq was deactivated as expected.
In general, we should fix the problem at the core API level instead of hacking individual drivers.
But more to the point, irq_dispose_mapping is not supposed to do anything with the an active irq, as it doesn't have the required information to safely remove it.
So calling irq_dispose_mapping on an interrupt that still has registered actions is a bug, and I'm not convinced we want to cater for such a case. Do you have a concrete example of some kernel code expecting this behaviour?
Thanks,
M.
> > BRs, > Yuanyuan > > >> -----Original Message----- >> From: Marc Zyngier [mailto:marc.zyngier@arm.com] >> Sent: 2019年1月9日 15:43 >> To: Zhao, Yuanyuan <yuanyuan.zhao@hxt-semitech.com> >> Cc: tglx@linutronix.de; jason@lakedaemon.net; linux- >> kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org; Zheng, Joey >> <yu.zheng@hxt-semitech.com>; Wang, Dongsheng <dongsheng.wang@hxt- >> semitech.com> >> Subject: Re: [RESEND 1/1] gic: its: Make sure a LPI is discarded before free. >> >> On Wed, 9 Jan 2019 11:53:27 +0800 >> Zhao Yuanyuan <yuanyuan.zhao@hxt-semitech.com> wrote: >> >> Hi Zhao, >> >>> Its device will be removed after all events be freed. >>> Undisarded events can lead to unpredictable behaviar. >>> >>> Signed-off-by: Zhao Yuanyuan <yuanyuan.zhao@hxt-semitech.com> >>> --- >>> drivers/irqchip/irq-gic-v3-its.c | 4 ++++ >>> 1 file changed, 4 insertions(+) >>> >>> diff --git a/drivers/irqchip/irq-gic-v3-its.c >>> b/drivers/irqchip/irq-gic-v3-its.c >>> index db20e99..4fee008 100644 >>> --- a/drivers/irqchip/irq-gic-v3-its.c >>> +++ b/drivers/irqchip/irq-gic-v3-its.c >>> @@ -2572,6 +2572,10 @@ static void its_irq_domain_free(struct >> irq_domain *domain, unsigned int virq, >>> virq + i); >>> u32 event = its_get_event_id(data); >>> >>> + /* Discard irq before free */ >>> + if (irqd_is_activated(d)) >>> + its_send_discard(its_dev, event); >>> + >>> /* Mark interrupt index as unused */ >>> clear_bit(event, its_dev->event_map.lpi_map); >>> >> >> But we already do send a discard on deactivate, which logically happens >> before we free the domain. So what are you fixing here? >> >> Thanks, >> >> M. >> -- >> Without deviation from the norm, progress is not possible.
-- Jazz is not dead. It just smells funny...
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