linux-kernel - [PATCH 4.4 087/118] irqchip/atmel-aic: Fix potential deadlock in ->xlate()

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Message-Id: <20160922172943.044210470@linuxfoundation.org>
Date:   Thu, 22 Sep 2016 19:29:47 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Marc Zyngier <marc.zyngier@....com>,
        Jason Cooper <jason@...edaemon.net>,
        Nicolas Ferre <nicolas.ferre@...el.com>,
        Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 4.4 087/118] irqchip/atmel-aic: Fix potential deadlock in ->xlate()

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Boris Brezillon <boris.brezillon@...e-electrons.com>

commit 5eb0d6eb3fac3daa60d9190eed9fa41cf809c756 upstream.

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
irq_gc_{lock_irqsave,unlock_irqrestore}() ones to prevent this bug from
happening.

Fixes: b1479ebb7720 ("irqchip: atmel-aic: Add atmel AIC/AIC5 drivers")
Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
Acked-by: Marc Zyngier <marc.zyngier@....com>
Cc: Jason Cooper <jason@...edaemon.net>
Cc: Nicolas Ferre <nicolas.ferre@...el.com>
Cc: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Link: http://lkml.kernel.org/r/1473775109-4192-2-git-send-email-boris.brezillon@free-electrons.com
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/irqchip/irq-atmel-aic.c  |    5 +++--
 drivers/irqchip/irq-atmel-aic5.c |    5 +++--
 2 files changed, 6 insertions(+), 4 deletions(-)

--- 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 i
 {
 	struct irq_domain_chip_generic *dgc = d->gc;
 	struct irq_chip_generic *gc;
+	unsigned long flags;
 	unsigned smr;
 	int idx;
 	int ret;
@@ -194,12 +195,12 @@ static int aic_irq_domain_xlate(struct i
 
 	gc = dgc->gc[idx];
 
-	irq_gc_lock(gc);
+	irq_gc_lock_irqsave(gc, flags);
 	smr = irq_reg_readl(gc, AT91_AIC_SMR(*out_hwirq));
 	ret = aic_common_set_priority(intspec[2], &smr);
 	if (!ret)
 		irq_reg_writel(gc, smr, AT91_AIC_SMR(*out_hwirq));
-	irq_gc_unlock(gc);
+	irq_gc_unlock_irqrestore(gc, flags);
 
 	return ret;
 }
--- 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
 				 unsigned int *out_type)
 {
 	struct irq_chip_generic *bgc = irq_get_domain_generic_chip(d, 0);
+	unsigned long flags;
 	unsigned smr;
 	int ret;
 
@@ -269,13 +270,13 @@ static int aic5_irq_domain_xlate(struct
 	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);
 	ret = aic_common_set_priority(intspec[2], &smr);
 	if (!ret)
 		irq_reg_writel(bgc, intspec[2] | smr, AT91_AIC5_SMR);
-	irq_gc_unlock(bgc);
+	irq_gc_unlock_irqrestore(bgc, flags);
 
 	return ret;
 }