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[PATCH v3 2/2] irqchip/atmel-aic: Fix potential deadlock in ->xlate()

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aic5_irq_domain_xlate() and aic_irq_domain_xlate() take the generic chip
lock without disabling interrupts, which can lead to a deadlock if an
interrupt occurs while the lock is held in one of these functions.

Replace irq_gc_{lock,unlock}() calls by
raw_spin_{lock_irqsave,unlock_irqrestore}() ones to prevent this bug from
happening.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Fixes: b1479ebb7720 ("irqchip: atmel-aic: Add atmel AIC/AIC5 drivers")
Cc: <stable@vger.kernel.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
---
Changes in v3:
- introduce and use the irq_gc_{lock_irqsave,unlock_irqrestore}() helpers

Changes in v2:
- add Marc's ack
- fix stable ML address

fixup! irqchip/atmel-aic: Fix potential deadlock in ->xlate()
---
 drivers/irqchip/irq-atmel-aic.c  | 5 +++--
 drivers/irqchip/irq-atmel-aic5.c | 5 +++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/irqchip/irq-atmel-aic.c b/drivers/irqchip/irq-atmel-aic.c
index 112e17c2768b..37f952dd9fc9 100644
--- a/drivers/irqchip/irq-atmel-aic.c
+++ b/drivers/irqchip/irq-atmel-aic.c
@@ -176,6 +176,7 @@ static int aic_irq_domain_xlate(struct irq_domain *d,
 {
 	struct irq_domain_chip_generic *dgc = d->gc;
 	struct irq_chip_generic *gc;
+	unsigned long flags;
 	unsigned smr;
 	int idx;
 	int ret;
@@ -194,11 +195,11 @@ static int aic_irq_domain_xlate(struct irq_domain *d,
 
 	gc = dgc->gc[idx];
 
-	irq_gc_lock(gc);
+	irq_gc_lock_irqsave(gc, flags);
 	smr = irq_reg_readl(gc, AT91_AIC_SMR(*out_hwirq));
 	aic_common_set_priority(intspec[2], &smr);
 	irq_reg_writel(gc, smr, AT91_AIC_SMR(*out_hwirq));
-	irq_gc_unlock(gc);
+	irq_gc_unlock_irqrestore(gc, flags);
 
 	return ret;
 }
diff --git a/drivers/irqchip/irq-atmel-aic5.c b/drivers/irqchip/irq-atmel-aic5.c
index 4f0d068e1abe..2a624d87a035 100644
--- a/drivers/irqchip/irq-atmel-aic5.c
+++ b/drivers/irqchip/irq-atmel-aic5.c
@@ -258,6 +258,7 @@ static int aic5_irq_domain_xlate(struct irq_domain *d,
 				 unsigned int *out_type)
 {
 	struct irq_chip_generic *bgc = irq_get_domain_generic_chip(d, 0);
+	unsigned long flags;
 	unsigned smr;
 	int ret;
 
@@ -269,12 +270,12 @@ static int aic5_irq_domain_xlate(struct irq_domain *d,
 	if (ret)
 		return ret;
 
-	irq_gc_lock(bgc);
+	irq_gc_lock_irqsave(bgc, flags);
 	irq_reg_writel(bgc, *out_hwirq, AT91_AIC5_SSR);
 	smr = irq_reg_readl(bgc, AT91_AIC5_SMR);
 	aic_common_set_priority(intspec[2], &smr);
 	irq_reg_writel(bgc, smr, AT91_AIC5_SMR);
-	irq_gc_unlock(bgc);
+	irq_gc_unlock_irqrestore(bgc, flags);
 
 	return ret;
 }
-- 
2.7.4

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[PATCH v3 1/2] genirq: Provide irq_gc_{lock_irqsave,unlock_irqrestore}() helpers Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-09-13 16:00 +0200
  [PATCH v3 2/2] irqchip/atmel-aic: Fix potential deadlock in ->xlate() Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-09-13 16:00 +0200
    Re: [PATCH v3 2/2] irqchip/atmel-aic: Fix potential deadlock in  ->xlate() Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-09-13 16:20 +0200
    [tip:irq/urgent] irqchip/atmel-aic: Fix potential deadlock in  ->xlate() tip-bot for Boris Brezillon <tipbot@zytor.com> - 2016-09-13 17:10 +0200
  [tip:irq/urgent] genirq: Provide  irq_gc_{lock_irqsave,unlock_irqrestore}() helpers tip-bot for Boris Brezillon <tipbot@zytor.com> - 2016-09-13 17:10 +0200

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