netdev - [RFC PATCH V2 09/11] xen: Clear IRQD_IRQ_STARTED flag during shutdown PIRQs

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Message-ID: <20200107234420.GA18738@dev-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com>
Date:   Tue, 7 Jan 2020 23:44:20 +0000
From:   Anchal Agarwal <anchalag@...zon.com>
To:     <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
        <hpa@...or.com>, <x86@...nel.org>, <boris.ostrovsky@...cle.com>,
        <jgross@...e.com>, <linux-pm@...r.kernel.org>,
        <linux-mm@...ck.org>, <kamatam@...zon.com>,
        <sstabellini@...nel.org>, <konrad.wilk@...cle.co>,
        <roger.pau@...rix.com>, <axboe@...nel.dk>, <davem@...emloft.net>,
        <rjw@...ysocki.net>, <len.brown@...el.com>, <pavel@....cz>,
        <peterz@...radead.org>, <eduval@...zon.com>, <sblbir@...zon.com>,
        <anchalag@...zon.com>, <xen-devel@...ts.xenproject.org>,
        <vkuznets@...hat.com>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <Woodhouse@...-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com>,
        <dwmw@...zon.co.uk>, <fllinden@...ozn.com>
CC:     <anchalag@...zon.com>
Subject: [RFC PATCH V2 09/11] xen: Clear IRQD_IRQ_STARTED flag during
 shutdown PIRQs

shutdown_pirq is invoked during hibernation path and hence
PIRQs should be restarted during resume.
Before this commit'020db9d3c1dc0a' xen/events: Fix interrupt lost
during irq_disable and irq_enable startup_pirq was automatically
called during irq_enable however, after this commit pirq's did not
get explicitly started once resumed from hibernation.

chip->irq_startup is called only if IRQD_IRQ_STARTED is unset during
irq_startup on resume. This flag gets cleared by free_irq->irq_shutdown
during suspend. free_irq() never gets explicitly called for ioapic-edge
and ioapic-level interrupts as respective drivers do nothing during
suspend/resume. So we shut them down explicitly in the first place in
syscore_suspend path to clear IRQ<>event channel mapping. shutdown_pirq
being called explicitly during suspend does not clear this flags, hence
.irq_enable is called in irq_startup during resume instead and pirq's
never start up.

Signed-off-by: Anchal Agarwal <anchalag@...zon.com>
---
 drivers/xen/events/events_base.c | 1 +
 include/linux/irq.h              | 1 +
 kernel/irq/chip.c                | 3 ++-
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index b893536d8af4..aae7c4997b51 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -1606,6 +1606,7 @@ void xen_shutdown_pirqs(void)
 			continue;
 
 		shutdown_pirq(irq_get_irq_data(info->irq));
+		irq_state_clr_started(irq_to_desc(info->irq));
 	}
 }
 
diff --git a/include/linux/irq.h b/include/linux/irq.h
index fb301cf29148..1e125cd22cf0 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -745,6 +745,7 @@ extern int irq_set_msi_desc(unsigned int irq, struct msi_desc *entry);
 extern int irq_set_msi_desc_off(unsigned int irq_base, unsigned int irq_offset,
 				struct msi_desc *entry);
 extern struct irq_data *irq_get_irq_data(unsigned int irq);
+extern void irq_state_clr_started(struct irq_desc *desc);
 
 static inline struct irq_chip *irq_get_chip(unsigned int irq)
 {
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index b76703b2c0af..3e8a36c673d6 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -173,10 +173,11 @@ static void irq_state_clr_masked(struct irq_desc *desc)
 	irqd_clear(&desc->irq_data, IRQD_IRQ_MASKED);
 }
 
-static void irq_state_clr_started(struct irq_desc *desc)
+void irq_state_clr_started(struct irq_desc *desc)
 {
 	irqd_clear(&desc->irq_data, IRQD_IRQ_STARTED);
 }
+EXPORT_SYMBOL_GPL(irq_state_clr_started);
 
 static void irq_state_set_started(struct irq_desc *desc)
 {
-- 
2.15.3.AMZN