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Subject[tip: irq/core] genirq: Sanitize state handling in check_irq_resend()
The following commit has been merged into the irq/core branch of tip:

Commit-ID: da90921acc62c71d27729ae211ccfda5370bf75b
Gitweb: https://git.kernel.org/tip/da90921acc62c71d27729ae211ccfda5370bf75b
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Fri, 06 Mar 2020 14:03:46 +01:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Sun, 08 Mar 2020 11:06:41 +01:00

genirq: Sanitize state handling in check_irq_resend()

The code sets IRQS_REPLAY unconditionally whether the resend happens or
not. That doesn't have bad side effects right now, but inconsistent state
is always a latent source of problems.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lkml.kernel.org/r/20200306130623.882129117@linutronix.de

---
kernel/irq/resend.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/kernel/irq/resend.c b/kernel/irq/resend.c
index a21fc4e..bef72dc 100644
--- a/kernel/irq/resend.c
+++ b/kernel/irq/resend.c
@@ -93,6 +93,8 @@ static int irq_sw_resend(struct irq_desc *desc)
*/
int check_irq_resend(struct irq_desc *desc)
{
+ int err = 0;
+
/*
* We do not resend level type interrupts. Level type interrupts
* are resent by hardware when they are still active. Clear the
@@ -106,13 +108,17 @@ int check_irq_resend(struct irq_desc *desc)
if (desc->istate & IRQS_REPLAY)
return -EBUSY;

- if (desc->istate & IRQS_PENDING) {
- desc->istate &= ~IRQS_PENDING;
- desc->istate |= IRQS_REPLAY;
+ if (!(desc->istate & IRQS_PENDING))
+ return 0;

- if (!desc->irq_data.chip->irq_retrigger ||
- !desc->irq_data.chip->irq_retrigger(&desc->irq_data))
- return irq_sw_resend(desc);
- }
- return 0;
+ desc->istate &= ~IRQS_PENDING;
+
+ if (!desc->irq_data.chip->irq_retrigger ||
+ !desc->irq_data.chip->irq_retrigger(&desc->irq_data))
+ err = irq_sw_resend(desc);
+
+ /* If the retrigger was successfull, mark it with the REPLAY bit */
+ if (!err)
+ desc->istate |= IRQS_REPLAY;
+ return err;
}
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