From: "Lothar Waßmann" <LW@KARO-electronics.de> To: linux-kernel@vger.kernel.org To: <linux-kernel@vger.kernel.org> Cc: "Lothar Waßmann" <LW@KARO-electronics.de>, "Thomas Gleixner" <tglx@linutronix.de>, "Lars-Peter Clausen" <lars@metafoo.de>, "Yong Zhang" <yong.zhang0@gmail.com>, linux-arm-kernel@lists.infradead.org Subject: [PATCH] genirq: Fix race condition in ONESHOT irq handler Date: Tue, 7 Feb 2012 14:38:41 +0100 [thread overview] Message-ID: <1328621921-17404-1-git-send-email-LW@KARO-electronics.de> (raw) In-Reply-To: 4F31220A.2050708@metafoo.de There is a race condition in the threaded IRQ handler code for oneshot interrupts that may lead to disabling an IRQ indefinitely. IRQs are masked before calling the hard-irq handler and are unmasked only after the soft-irq handler has been run. Thus if the hard-irq handler returns IRQ_HANDLED instead of IRQ_WAKE_THREAD, meaning the soft-irq will not be called, the interrupt will remain masked forever. This can happen due to a short pulse on the interrupt line, that triggers the interrupt logic, but goes undetected by the hard-irq handler. The problem can be reproduced with the TSC2007 touch controller driver that uses ONESHOT interrupts. The problem arises also with interrupt controllers that latch a level triggered IRQ until it is acknowledged (like the i.MX28 does). In this case the IRQ status bit will remain asserted after the soft-irq finishes and retrigger the interrupt while the interrupt line is already deasserted. Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de> --- kernel/irq/chip.c | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-) diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c index f7c543a..74fdef9 100644 --- a/kernel/irq/chip.c +++ b/kernel/irq/chip.c @@ -343,6 +343,8 @@ EXPORT_SYMBOL_GPL(handle_simple_irq); void handle_level_irq(unsigned int irq, struct irq_desc *desc) { + irqreturn_t ret; + raw_spin_lock(&desc->lock); mask_ack_irq(desc); @@ -360,10 +362,13 @@ handle_level_irq(unsigned int irq, struct irq_desc *desc) if (unlikely(!desc->action || irqd_irq_disabled(&desc->irq_data))) goto out_unlock; - handle_irq_event(desc); + ret = handle_irq_event(desc); - if (!irqd_irq_disabled(&desc->irq_data) && !(desc->istate & IRQS_ONESHOT)) + if (!irqd_irq_disabled(&desc->irq_data) && + (!(desc->istate & IRQS_ONESHOT) || + !(ret & IRQ_WAKE_THREAD))) unmask_irq(desc); + out_unlock: raw_spin_unlock(&desc->lock); } -- 1.7.2.5
WARNING: multiple messages have this Message-ID (diff)
From: LW@KARO-electronics.de (Lothar Waßmann) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] genirq: Fix race condition in ONESHOT irq handler Date: Tue, 7 Feb 2012 14:38:41 +0100 [thread overview] Message-ID: <1328621921-17404-1-git-send-email-LW@KARO-electronics.de> (raw) In-Reply-To: 4F31220A.2050708@metafoo.de There is a race condition in the threaded IRQ handler code for oneshot interrupts that may lead to disabling an IRQ indefinitely. IRQs are masked before calling the hard-irq handler and are unmasked only after the soft-irq handler has been run. Thus if the hard-irq handler returns IRQ_HANDLED instead of IRQ_WAKE_THREAD, meaning the soft-irq will not be called, the interrupt will remain masked forever. This can happen due to a short pulse on the interrupt line, that triggers the interrupt logic, but goes undetected by the hard-irq handler. The problem can be reproduced with the TSC2007 touch controller driver that uses ONESHOT interrupts. The problem arises also with interrupt controllers that latch a level triggered IRQ until it is acknowledged (like the i.MX28 does). In this case the IRQ status bit will remain asserted after the soft-irq finishes and retrigger the interrupt while the interrupt line is already deasserted. Signed-off-by: Lothar Wa?mann <LW@KARO-electronics.de> --- kernel/irq/chip.c | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-) diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c index f7c543a..74fdef9 100644 --- a/kernel/irq/chip.c +++ b/kernel/irq/chip.c @@ -343,6 +343,8 @@ EXPORT_SYMBOL_GPL(handle_simple_irq); void handle_level_irq(unsigned int irq, struct irq_desc *desc) { + irqreturn_t ret; + raw_spin_lock(&desc->lock); mask_ack_irq(desc); @@ -360,10 +362,13 @@ handle_level_irq(unsigned int irq, struct irq_desc *desc) if (unlikely(!desc->action || irqd_irq_disabled(&desc->irq_data))) goto out_unlock; - handle_irq_event(desc); + ret = handle_irq_event(desc); - if (!irqd_irq_disabled(&desc->irq_data) && !(desc->istate & IRQS_ONESHOT)) + if (!irqd_irq_disabled(&desc->irq_data) && + (!(desc->istate & IRQS_ONESHOT) || + !(ret & IRQ_WAKE_THREAD))) unmask_irq(desc); + out_unlock: raw_spin_unlock(&desc->lock); } -- 1.7.2.5
next prev parent reply other threads:[~2012-02-07 13:38 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-02-06 8:14 [BUG] genirq: Race condition in ONESHOT IRQ handler disabling IRQ forever =?utf-8?Q?Lothar_Wa=C3=9Fmann?= 2012-02-06 8:14 ` =?utf-8?Q?Lothar_Wa=C3=9Fmann?= 2012-02-06 10:42 ` Lars-Peter Clausen 2012-02-06 10:42 ` Lars-Peter Clausen 2012-02-07 9:03 ` Yong Zhang 2012-02-07 9:03 ` Yong Zhang 2012-02-07 10:01 ` Lothar Waßmann 2012-02-07 10:01 ` Lothar Waßmann 2012-02-07 12:34 ` Yong Zhang 2012-02-07 12:34 ` Yong Zhang 2012-02-07 12:52 ` Lothar Waßmann 2012-02-07 12:52 ` Lothar Waßmann 2012-02-07 13:07 ` Lars-Peter Clausen 2012-02-07 13:07 ` Lars-Peter Clausen 2012-02-07 13:38 ` Lothar Waßmann [this message] 2012-02-07 13:38 ` [PATCH] genirq: Fix race condition in ONESHOT irq handler Lothar Waßmann 2012-02-07 17:03 ` Thomas Gleixner 2012-02-07 17:03 ` Thomas Gleixner 2012-02-08 6:05 ` Lothar Waßmann 2012-02-08 6:05 ` Lothar Waßmann 2012-02-08 10:38 ` Thomas Gleixner 2012-02-08 10:38 ` Thomas Gleixner 2012-02-09 8:40 ` Lothar Waßmann 2012-02-09 8:40 ` Lothar Waßmann
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