Re: [PATCH 1/2] Add user interrupt handling code for mach pathway

[Samuel Thibault]

Getting closer! :D

Damien Zammit, le mar. 30 mars 2021 01:23:55 +1100, a ecrit:
> +  struct intr_list *handler;
> +  struct intr_list **prev = &user_intr_handlers[id];
> +  user_intr_t *e;
> +  spl_t s;
> +
> +  s = splhigh();
> +
> +  for (handler = user_intr_handlers[id]; handler; handler = handler->next)

I'd say use *prev in the initialization part of the for loop, that will
be more robust to maintenance.


> +  for (iter = *head; iter; iter = iter->next)
> +    {
> +      if (!(iter->flags & flags & SA_SHIRQ))
> +        {

You don't actually need to iterate: if the first entry has flags without
SA_SHIRQ, we can't share. Otherwise (empty or several entries and the
first has SA_SHIRQ), we can share.

> +          mach_print ("Cannot share irq\n");
> +          return D_ALREADY_OPEN;
> +        }
> +    }
> +
> +  new = (struct intr_list *)kalloc (sizeof (struct intr_list));
> +  new->user_intr = user_intr;
> +  new->flags = flags;
> +  new->next = *head;
> +  *head = new;

I believe you need to update next and *head in the splhigh section,
otherwise you risk getting interrupted, user intr delivery code to
trigger, and mayhem happen.

> +  s = splhigh();