linux-kernel - [PATCH] xen/events: Fix interrupt lost during irq_disable and irq

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Date:   Sun, 30 Jul 2017 00:59:57 +0800
From:   Liu Shuo <shuo.a.liu@...el.com>
To:     linux-kernel@...r.kernel.org
Cc:     Liu Shuo <shuo.a.liu@...el.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        David Vrabel <david.vrabel@...rix.com>,
        Ingo Molnar <mingo@...nel.org>,
        Anoob Soman <anoob.soman@...rix.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Len Brown <len.brown@...el.com>,
        KarimAllah Ahmed <karahmed@...zon.de>,
        xen-devel@...ts.xenproject.org (moderated list:XEN HYPERVISOR INTERFACE)
Subject: [PATCH] xen/events: Fix interrupt lost during irq_disable and irq_enable

Here is a device has xen-pirq-MSI interrupt. Dom0 might lost interrupt
during driver irq_disable/irq_enable. Here is the scenario,
 1. irq_disable -> disable_dynirq -> mask_evtchn(irq channel)
 2. dev interrupt raised by HW and Xen mark its evtchn as pending
 3. irq_enable -> startup_pirq -> eoi_pirq ->
    clear_evtchn(channel of irq) -> clear pending status
 4. consume_one_event process the irq event without pending bit assert
    which result in interrupt lost once
 5. No HW interrupt raising anymore.

Now use enable_dynirq for enable_pirq of xen_pirq_chip to remove
eoi_pirq when irq_enable.

Signed-off-by: Liu Shuo <shuo.a.liu@...el.com>
---
 drivers/xen/events/events_base.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index bae1f5d3..2d43118 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -574,7 +574,7 @@ static void shutdown_pirq(struct irq_data *data)
 
 static void enable_pirq(struct irq_data *data)
 {
-	startup_pirq(data);
+	enable_dynirq(data);
 }
 
 static void disable_pirq(struct irq_data *data)
-- 
1.9.4