irqchip/qcom-pdc: Fix broken locking
authorMarc Zyngier <maz@kernel.org>
Thu, 24 Feb 2022 10:12:25 +0000 (10:12 +0000)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 8 Apr 2022 12:40:31 +0000 (14:40 +0200)
[ 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@kernel.org>
Reviewed-by: Maulik Shah <quic_mkshah@quicinc.com>
Link: https://lore.kernel.org/r/20220224101226.88373-5-maz@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
drivers/irqchip/qcom-pdc.c

index 5dc63c20b67ea93730c27161015c4f7f0672b51f..fc747b7f498302e8b4daf0d2a6b01a28abddcb69 100644 (file)
@@ -74,17 +74,18 @@ static int qcom_pdc_gic_set_irqchip_state(struct irq_data *d,
 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)