Re: [PATCH v6 04/10] genirq: Introduce common irq_force_complete_move() implementation

[Frank Scheiner <frank.scheiner@web.de>]

Hi there,

this change, specfically the introduction of irq_force_complete_move()
to `kernel/irq/migration.c`, strangely breaks our builds for the hp-sim
platform (i.e. Linux/ia64 for Ski):

```
  CC      kernel/irq/affinity.o
kernel/irq/migration.c: In function 'irq_force_complete_move':
kernel/irq/migration.c:40:72: error: 'struct irq_data' has no member named 'parent_data'
   40 |         for (struct irq_data *d = irq_desc_get_irq_data(desc); d; d = d->parent_data) {
      |                                                                        ^~
make[4]: *** [scripts/Makefile.build:207: kernel/irq/migration.o] Error 1
```

The reason seems to be that "d->parent_data" (i.e.
"irq_data.parent_data") is used unguarded in this function:

```
void irq_force_complete_move(struct irq_desc *desc)
{
    for (struct irq_data *d = irq_desc_get_irq_data(desc); d; d = d->parent_data) {
        if (d->chip && d->chip->irq_force_complete_move) {
            d->chip->irq_force_complete_move(d);
            return;
        }
    }
}
```

...but "parent_data" is only present in `include/linux/irq.h` if
`CONFIG_IRQ_DOMAIN_HIERARCHY` was selected.

```
struct irq_data {
    u32            mask;
    unsigned int        irq;
    irq_hw_number_t        hwirq;
    struct irq_common_data    *common;
    struct irq_chip        *chip;
    struct irq_domain    *domain;
#ifdef    CONFIG_IRQ_DOMAIN_HIERARCHY
    struct irq_data        *parent_data;
#endif
    void            *chip_data;
};
```

So I guess, either the requirement in `linux/include/linux/irq.h` needs
to go, or the use of "d->parent_data" or the whole of
irq_force_complete_move() and its use needs to be guarded as well.

Cheers,
Frank