[PATCH v3 1/2] genirq: Provide irq_gc_{lock_irqsave,unlock_irqrestore}() helpers

[PATCH v3 1/2] genirq: Provide irq_gc_{lock_irqsave,unlock_irqrestore}() helpers

[Boris Brezillon]

Some irqchip drivers need to take the generic chip lock outside of the
irq context.

Provide the irq_gc_{lock_irqsave,unlock_irqrestore}() helpers to allow
one to disable irqs while entering a critical section protected by
gc->lock.

Note that we do not provide optimized version of these helpers for !SMP,
because they are not called from the hot-path.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: <stable@vger.kernel.org>
---
 include/linux/irq.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index b52424eaa0ed..b13668f97648 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -945,6 +945,12 @@ static inline void irq_gc_lock(struct irq_chip_generic *gc) { }
 static inline void irq_gc_unlock(struct irq_chip_generic *gc) { }
 #endif
 
+#define irq_gc_lock_irqsave(gc, flags)	\
+	raw_spin_lock_irqsave(&(gc)->lock, flags)
+
+#define irq_gc_unlock_irqrestore(gc, flags)	\
+	raw_spin_unlock_irqrestore(&(gc)->lock, flags)
+
 static inline void irq_reg_writel(struct irq_chip_generic *gc,
 				  u32 val, int reg_offset)
 {
-- 
2.7.4

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

[Boris Brezillon]

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

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

[Boris Brezillon]

On Tue, 13 Sep 2016 15:58:29 +0200
Boris Brezillon <boris.brezillon@free-electrons.com> wrote:

> 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

Sorry, I forgot to update my commit message: s/raw_spin_/irq_gc_/.
Thomas, can you fix that when applying, or should I send a new version?

> 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;
>  }

[tip:irq/urgent] genirq: Provide irq_gc_{lock_irqsave,unlock_irqrestore}() helpers

[tip-bot for Boris Brezillon]

Commit-ID:  ebf9ff753c041b296241990aef76163bbb2cc9c8
Gitweb:     http://git.kernel.org/tip/ebf9ff753c041b296241990aef76163bbb2cc9c8
Author:     Boris Brezillon <boris.brezillon@free-electrons.com>
AuthorDate: Tue, 13 Sep 2016 15:58:28 +0200
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 13 Sep 2016 16:57:40 +0200

genirq: Provide irq_gc_{lock_irqsave,unlock_irqrestore}() helpers

Some irqchip drivers need to take the generic chip lock outside of the
irq context.

Provide the irq_gc_{lock_irqsave,unlock_irqrestore}() helpers to allow
one to disable irqs while entering a critical section protected by
gc->lock.

Note that we do not provide optimized version of these helpers for !SMP,
because they are not called from the hot-path.

[ tglx: Added a comment when these helpers should be [not] used ]

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: stable@vger.kernel.org
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Link: http://lkml.kernel.org/r/1473775109-4192-1-git-send-email-boris.brezillon@free-electrons.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 include/linux/irq.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index b52424e..0ac26c8 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -945,6 +945,16 @@ static inline void irq_gc_lock(struct irq_chip_generic *gc) { }
 static inline void irq_gc_unlock(struct irq_chip_generic *gc) { }
 #endif
 
+/*
+ * The irqsave variants are for usage in non interrupt code. Do not use
+ * them in irq_chip callbacks. Use irq_gc_lock() instead.
+ */
+#define irq_gc_lock_irqsave(gc, flags)	\
+	raw_spin_lock_irqsave(&(gc)->lock, flags)
+
+#define irq_gc_unlock_irqrestore(gc, flags)	\
+	raw_spin_unlock_irqrestore(&(gc)->lock, flags)
+
 static inline void irq_reg_writel(struct irq_chip_generic *gc,
 				  u32 val, int reg_offset)
 {

[tip:irq/urgent] irqchip/atmel-aic: Fix potential deadlock in ->xlate()

[tip-bot for Boris Brezillon]

Commit-ID:  5eb0d6eb3fac3daa60d9190eed9fa41cf809c756
Gitweb:     http://git.kernel.org/tip/5eb0d6eb3fac3daa60d9190eed9fa41cf809c756
Author:     Boris Brezillon <boris.brezillon@free-electrons.com>
AuthorDate: Tue, 13 Sep 2016 15:58:29 +0200
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 13 Sep 2016 16:57:40 +0200

irqchip/atmel-aic: Fix potential deadlock in ->xlate()

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@free-electrons.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: stable@vger.kernel.org
Cc: Alexandre Belloni <alexandre.belloni@free-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@linutronix.de>

---
 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 112e17c..37f952d 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 4f0d068..2a624d8 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;
 }