[tip: irq/msi] irqchip/sifive-plic: Improve locking safety by using irqsave/irqrestore

tip-bot2 for Anup Patel
2024-02-23T09:44:01Z

The following commit has been merged into the irq/msi branch of tip:

Commit-ID: abb7205794900503d6358ef1fb645373753a794d
Gitweb: https://git.kernel.org/tip/abb7205794900503d6358ef1fb645373753a794d
Author: Anup Patel <apatel@ventanamicro.com>
AuthorDate: Thu, 22 Feb 2024 15:09:55 +05:30
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Fri, 23 Feb 2024 10:18:44 +01:00

irqchip/sifive-plic: Improve locking safety by using irqsave/irqrestore

Now that PLIC driver is probed as a regular platform driver, the lock
dependency validator complains about the safety of handler->enable_lock
usage:

[ 0.956775] Possible interrupt unsafe locking scenario:

[ 0.956998] CPU0 CPU1
[ 0.957247] ---- ----
[ 0.957439] lock(&handler->enable_lock);
[ 0.957607] local_irq_disable();
[ 0.957793] lock(&irq_desc_lock_class);
[ 0.958021] lock(&handler->enable_lock);
[ 0.958246] <Interrupt>
[ 0.958342] lock(&irq_desc_lock_class);
[ 0.958501]
*** DEADLOCK ***

To address above, use raw_spin_lock_irqsave/unlock_irqrestore() instead
of raw_spin_lock/unlock().

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240222094006.1030709-8-apatel@ventanamicro.com

---
drivers/irqchip/irq-sifive-plic.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
index 474ddc3..601000d 100644
--- a/drivers/irqchip/irq-sifive-plic.c
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -103,9 +103,11 @@ static void __plic_toggle(void __iomem *enable_base, int hwirq, int enable)

static void plic_toggle(struct plic_handler *handler, int hwirq, int enable)
{
- raw_spin_lock(&handler->enable_lock);
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&handler->enable_lock, flags);
__plic_toggle(handler->enable_base, hwirq, enable);
- raw_spin_unlock(&handler->enable_lock);
+ raw_spin_unlock_irqrestore(&handler->enable_lock, flags);
}

static inline void plic_irq_toggle(const struct cpumask *mask,
@@ -236,6 +238,7 @@ static int plic_irq_set_type(struct irq_data *d, unsigned int type)
static int plic_irq_suspend(void)
{
unsigned int i, cpu;
+ unsigned long flags;
u32 __iomem *reg;
struct plic_priv *priv;

@@ -253,12 +256,12 @@ static int plic_irq_suspend(void)
if (!handler->present)
continue;

- raw_spin_lock(&handler->enable_lock);
+ raw_spin_lock_irqsave(&handler->enable_lock, flags);
for (i = 0; i < DIV_ROUND_UP(priv->nr_irqs, 32); i++) {
reg = handler->enable_base + i * sizeof(u32);
handler->enable_save[i] = readl(reg);
}
- raw_spin_unlock(&handler->enable_lock);
+ raw_spin_unlock_irqrestore(&handler->enable_lock, flags);
}

return 0;
@@ -267,6 +270,7 @@ static int plic_irq_suspend(void)
static void plic_irq_resume(void)
{
unsigned int i, index, cpu;
+ unsigned long flags;
u32 __iomem *reg;
struct plic_priv *priv;

@@ -284,12 +288,12 @@ static void plic_irq_resume(void)
if (!handler->present)
continue;

- raw_spin_lock(&handler->enable_lock);
+ raw_spin_lock_irqsave(&handler->enable_lock, flags);
for (i = 0; i < DIV_ROUND_UP(priv->nr_irqs, 32); i++) {
reg = handler->enable_base + i * sizeof(u32);
writel(handler->enable_save[i], reg);
}
- raw_spin_unlock(&handler->enable_lock);
+ raw_spin_unlock_irqrestore(&handler->enable_lock, flags);
}
}