Hi Evan, On 10/8/19 3:36 PM, Evan Green wrote: > rmi_process_interrupt_requests() calls handle_nested_irq() for > each interrupt status bit it finds. If the irq domain mapping for > this bit had not yet been set up, then it ends up calling > handle_nested_irq(0), which causes a NULL pointer dereference. > > There's already code that masks the irq_status bits coming out of the > hardware with current_irq_mask, presumably to avoid this situation. > However current_irq_mask seems to more reflect the actual mask set > in the hardware rather than the IRQs software has set up and registered > for. For example, in rmi_driver_reset_handler(), the current_irq_mask > is initialized based on what is read from the hardware. If the reset > value of this mask enables IRQs that Linux has not set up yet, then > we end up in this situation. > > There appears to be a third unused bitmask that used to serve this > purpose, fn_irq_bits. Use that bitmask instead of current_irq_mask > to avoid calling handle_nested_irq() on IRQs that have not yet been > set up.
Yes, it looks like the code which ensured that there was a function handler to handle the IRQ was removed when the driver switched to using an irq domain. Setting the fn_irq_bits and using them instead of current_irq_mask in rmi_process_interrupt_requests() makes sense to me. Andrew > Signed-off-by: Evan Green <[email protected]> Reviewed-by: Andrew Duggan <[email protected]> > --- > > drivers/input/rmi4/rmi_driver.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/input/rmi4/rmi_driver.c b/drivers/input/rmi4/rmi_driver.c > index 772493b1f665..190b9974526b 100644 > --- a/drivers/input/rmi4/rmi_driver.c > +++ b/drivers/input/rmi4/rmi_driver.c > @@ -146,7 +146,7 @@ static int rmi_process_interrupt_requests(struct > rmi_device *rmi_dev) > } > > mutex_lock(&data->irq_mutex); > - bitmap_and(data->irq_status, data->irq_status, data->current_irq_mask, > + bitmap_and(data->irq_status, data->irq_status, data->fn_irq_bits, > data->irq_count); > /* > * At this point, irq_status has all bits that are set in the > @@ -385,6 +385,8 @@ static int rmi_driver_set_irq_bits(struct rmi_device > *rmi_dev, > bitmap_copy(data->current_irq_mask, data->new_irq_mask, > data->num_of_irq_regs); > > + bitmap_or(data->fn_irq_bits, data->fn_irq_bits, mask, data->irq_count); > + > error_unlock: > mutex_unlock(&data->irq_mutex); > return error; > @@ -398,6 +400,8 @@ static int rmi_driver_clear_irq_bits(struct rmi_device > *rmi_dev, > struct device *dev = &rmi_dev->dev; > > mutex_lock(&data->irq_mutex); > + bitmap_andnot(data->fn_irq_bits, > + data->fn_irq_bits, mask, data->irq_count); > bitmap_andnot(data->new_irq_mask, > data->current_irq_mask, mask, data->irq_count); >
