On Tue, Feb 11, 2020 at 09:59:30AM +0100, Thomas Gleixner wrote:

Uwe Kleine-König [off-list ref] writes:

quoted

On Tue, Feb 11, 2020 at 10:35:44AM +0300, Dan Carpenter wrote:

quoted

Smatch thinks that gpio_siox_irq_set_type() can be called from
probe_irq_on().  In that case the call to spin_unlock_irq() would
renable IRQs too early.

Fixes: be8c8facc707 ("gpio: new driver to work with a 8x12 siox")
Signed-off-by: Dan Carpenter <redacted>
---
 drivers/gpio/gpio-siox.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-siox.c b/drivers/gpio/gpio-siox.c
index 311f66757b92..578b71760939 100644
--- a/drivers/gpio/gpio-siox.c
+++ b/drivers/gpio/gpio-siox.c

@@ -133,10 +133,11 @@ static int gpio_siox_irq_set_type(struct irq_data *d, u32 type)
 	struct irq_chip *ic = irq_data_get_irq_chip(d);
 	struct gpio_siox_ddata *ddata =
 		container_of(ic, struct gpio_siox_ddata, ichip);
+	unsigned long flags;
 
-	spin_lock_irq(&ddata->irqlock);
+	spin_lock_irqsave(&ddata->irqlock, flags);
 	ddata->irq_type[d->hwirq] = type;
-	spin_unlock_irq(&ddata->irqlock);
+	spin_unlock_irqrestore(&ddata->irqlock, flags);

"Normally" the .irq_set_type() callback is called from irq_set_irq_type.
There desc->lock is taken with raw_spin_lock_irqsave (as part of
irq_get_desc_buslock()), so I assume irqs are always disabled when the
type changes? tglx?

If so, the better fix would be to change to spin_lock/spin_unlock
instead. Also given that a raw spinlock is taken, the irqlock here
should be changed to a raw one, too?

Indeed. Looking at the driver, all of the spin_lock_irq() usage in the
irqchip callbacks is broken.

So this needs two changes:

   1) Convert to raw spin lock, as this won't work on RT otherwise

   2) s/lock_irq/lock/ for all irqchip callbacks.

Are you sure about the calls in gpio_siox_get_data()? This is only
called by siox_poll() which doesn't disable irqs.
 
Best regards
Uwe

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Pengutronix e.K.                           | Uwe Kleine-König            |
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