Re: [PATCH 2/4] binder: migrate ioctl to new PF_SPAM_DETECTION

Alice Ryhl
2024-04-18T08:12:27Z

Carlos Llamas <cmllamas@google.com> writes:
> @@ -5553,7 +5553,8 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> goto err;
> }
> binder_inner_proc_lock(proc);
> - proc->oneway_spam_detection_enabled = (bool)enable;
> + proc->flags &= ~PF_SPAM_DETECTION;
> + proc->flags |= enable & PF_SPAM_DETECTION;

The bitwise and in `enable & PF_SPAM_DETECTION` only works because
PF_SPAM_DETECTION happens to be equal to 1. This seems pretty fragile to
me. Would you be willing to do this instead?

proc->flags &= ~PF_SPAM_DETECTION;
if (enable)
proc->flags |= PF_SPAM_DETECTION;

Carlos Llamas <cmllamas@google.com> writes:
> - if (proc->oneway_spam_detection_enabled &&
> - w->type == BINDER_WORK_TRANSACTION_ONEWAY_SPAM_SUSPECT)
> + if (proc->flags & PF_SPAM_DETECTION &&
> + w->type == BINDER_WORK_TRANSACTION_ONEWAY_SPAM_SUSPECT)

Maybe I am just not sufficiently familiar with C, but I had to look up
the operator precedence rules for this one. Could we add parenthesises
around `proc->flags & PF_SPAM_DETECTION`? Or even define a macro for it?

Alice