From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aniruddha Banerjee Subject: [RFC PATCH] irqchip: arm-gic: take gic_lock when updating irq type Date: Thu, 22 Mar 2018 10:28:59 +0000 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Return-path: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Marc Zyngier Cc: "linux-kernel@vger.kernel.org" , "linux-tegra@vger.kernel.org" , Jonathan Hunter , Stephen Warren , Thierry Reding , Vipin Kumar List-Id: linux-tegra@vger.kernel.org The kernel documentation states that the irq-chip driver should handle the locking of the irq-chip registers. In the irq-gic, the accesses to the irqchip are seemingly not protected and multiple writes to SPIs from different irq descriptors do RMW requests without taking the irq-chip lock. When multiple irqs call the request_irq at the same time, there can be a simultaneous write at the gic distributor, leading to a race. Acquire the irq_controller lock when the irq_type is updated. This patch is only for GICv2; however, I have noticed a similar implementation in GICv3. This patch is sent as an RFC in case I am missing anything. Signed-off-by: Aniruddha Banerjee --- drivers/irqchip/irq-gic.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c index 4c797b43614d..61380f5a2254 100644 --- a/drivers/irqchip/irq-gic.c +++ b/drivers/irqchip/irq-gic.c @@ -67,6 +67,8 @@ static void gic_check_cpu_features(void) #define gic_check_cpu_features() do { } while(0) #endif +static DEFINE_RAW_SPINLOCK(irq_controller_lock); + union gic_base { void __iomem *common_base; void __percpu * __iomem *percpu_base; @@ -529,6 +531,7 @@ static int gic_set_type(struct irq_data *d, unsigned int type) { void __iomem *base = gic_dist_base(d); unsigned int gicirq = gic_irq(d); + int ret; /* Interrupt configuration for SGIs can't be changed */ if (gicirq < 16) @@ -539,7 +542,11 @@ static int gic_set_type(struct irq_data *d, unsigned int type) type != IRQ_TYPE_EDGE_RISING) return -EINVAL; - return gic_configure_irq(gicirq, type, base, NULL); + raw_spin_lock(&irq_controller_lock); + ret = gic_configure_irq(gicirq, type, base, NULL); + raw_spin_unlock(&irq_controller_lock); + + return ret; } static int gic_irq_set_vcpu_affinity(struct irq_data *d, void *vcpu) -- 2.15.1