Commit f1a63db6 authored by Chengfeng Ye's avatar Chengfeng Ye Committed by Lee Jones
Browse files

mfd: qcom-pm8xxx: Fix potential deadlock on &chip->pm_irq_lock 



As &chip->pm_irq_lock is acquired by pm8xxx_irq_handler() under irq
context, other process context code should disable irq before acquiring
the lock.

Since .irq_set_type and .irq_get_irqchip_state callbacks are generally
executed from process context without irq disabled by default, the same
lock acquision should disable irq.

Possible deadlock scenario
pm8xxx_irq_set_type()
    -> pm8xxx_config_irq()
    -> spin_lock(&chip->pm_irq_lock)
        <irq interrupt>
        -> pm8xxx_irq_handler()
        -> pm8xxx_irq_master_handler()
        -> pm8xxx_irq_block_handler()
        -> pm8xxx_read_block_irq()
        -> spin_lock(&chip->pm_irq_lock) (deadlock here)

This flaw was found using an experimental static analysis tool we are
developing for irq-related deadlock.

Fix the potential deadlock by spin_lock_irqsave().

Signed-off-by: default avatarChengfeng Ye <dg573847474@gmail.com>
Reviewed-by: default avatarBjorn Andersson <quic_bjorande@quicinc.com>
Link: https://lore.kernel.org/r/20230720071330.50382-1-dg573847474@gmail.com


Signed-off-by: default avatarLee Jones <lee@kernel.org>
parent 506fbc6b

drivers/mfd/qcom-pm8xxx.c

+6 −4
Original line number Diff line number Diff line
@@ -103,8 +103,9 @@ static int 
pm8xxx_config_irq(struct pm_irq_chip *chip, unsigned int bp, unsigned int cp)

{

	int	rc;

	unsigned long flags;



	spin_lock(&chip->pm_irq_lock);

	spin_lock_irqsave(&chip->pm_irq_lock, flags);

	rc = regmap_write(chip->regmap, SSBI_REG_ADDR_IRQ_BLK_SEL, bp);

	if (rc) {

		pr_err("Failed Selecting Block %d rc=%d\n", bp, rc);
@@ -116,7 +117,7 @@ pm8xxx_config_irq(struct pm_irq_chip *chip, unsigned int bp, unsigned int cp) 
	if (rc)

		pr_err("Failed Configuring IRQ rc=%d\n", rc);

bail:

	spin_unlock(&chip->pm_irq_lock);

	spin_unlock_irqrestore(&chip->pm_irq_lock, flags);

	return rc;

}
@@ -321,6 +322,7 @@ static int pm8xxx_irq_get_irqchip_state(struct irq_data *d, 
	struct pm_irq_chip *chip = irq_data_get_irq_chip_data(d);

	unsigned int pmirq = irqd_to_hwirq(d);

	unsigned int bits;

	unsigned long flags;

	int irq_bit;

	u8 block;

	int rc;
@@ -331,7 +333,7 @@ static int pm8xxx_irq_get_irqchip_state(struct irq_data *d, 
	block = pmirq / 8;

	irq_bit = pmirq % 8;



	spin_lock(&chip->pm_irq_lock);

	spin_lock_irqsave(&chip->pm_irq_lock, flags);

	rc = regmap_write(chip->regmap, SSBI_REG_ADDR_IRQ_BLK_SEL, block);

	if (rc) {

		pr_err("Failed Selecting Block %d rc=%d\n", block, rc);
@@ -346,7 +348,7 @@ static int pm8xxx_irq_get_irqchip_state(struct irq_data *d, 


	*state = !!(bits & BIT(irq_bit));

bail:

	spin_unlock(&chip->pm_irq_lock);

	spin_unlock_irqrestore(&chip->pm_irq_lock, flags);



	return rc;

}