This is a note to let you know that I've just added the patch titled irqchip/qcom-pdc: Fix broken locking to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: irqchip-qcom-pdc-fix-broken-locking.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 0fe9e2a3211b2afaa26ce196eecd72536241a2ae Author: Marc Zyngier <maz@xxxxxxxxxx> Date: Thu Feb 24 10:12:25 2022 +0000 irqchip/qcom-pdc: Fix broken locking [ Upstream commit a6aca2f460e203781dc41391913cc5b54f4bc0ce ] pdc_enable_intr() serves as a primitive to qcom_pdc_gic_{en,dis}able, and has a raw spinlock for mutual exclusion, which is uses with interruptible primitives. This means that this critical section can itself be interrupted. Should the interrupt also be a PDC interrupt, and the endpoint driver perform an irq_disable() on that interrupt, we end-up in a deadlock. Fix this by using the irqsave/irqrestore variants of the locking primitives. Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> Reviewed-by: Maulik Shah <quic_mkshah@xxxxxxxxxxx> Link: https://lore.kernel.org/r/20220224101226.88373-5-maz@xxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/irqchip/qcom-pdc.c b/drivers/irqchip/qcom-pdc.c index 173e6520e06e..c0b457f26ec4 100644 --- a/drivers/irqchip/qcom-pdc.c +++ b/drivers/irqchip/qcom-pdc.c @@ -56,17 +56,18 @@ static u32 pdc_reg_read(int reg, u32 i) static void pdc_enable_intr(struct irq_data *d, bool on) { int pin_out = d->hwirq; + unsigned long flags; u32 index, mask; u32 enable; index = pin_out / 32; mask = pin_out % 32; - raw_spin_lock(&pdc_lock); + raw_spin_lock_irqsave(&pdc_lock, flags); enable = pdc_reg_read(IRQ_ENABLE_BANK, index); enable = on ? ENABLE_INTR(enable, mask) : CLEAR_INTR(enable, mask); pdc_reg_write(IRQ_ENABLE_BANK, index, enable); - raw_spin_unlock(&pdc_lock); + raw_spin_unlock_irqrestore(&pdc_lock, flags); } static void qcom_pdc_gic_disable(struct irq_data *d)