Messages in this thread | | | From | Alice Ryhl <> | Date | Mon, 22 Apr 2024 10:52:57 +0200 | Subject | Re: [PATCH 2/4] binder: migrate ioctl to new PF_SPAM_DETECTION |
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On Sun, Apr 21, 2024 at 1:49 AM Carlos Llamas <cmllamas@google.com> wrote: > > On Thu, Apr 18, 2024 at 08:12:22AM +0000, Alice Ryhl wrote: > > 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; > > > > I don't think it is fragile since PF_SPAM_DETECTION is fixed. However, > I agree the code is missing context about the flag being bit 0 and your > version addresses this problem. So I'll take it for v2, thanks!
Thanks! By fragile I mean that it could result in future mistakes, e.g. somebody could copy this code and use it elsewhere with a different bit flag that might not be bit 0.
> > 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? > > I think this is fairly common in C but I can definitly add the extra > paranthesis if it helps.
Yeah, makes sense. Thanks!
With the mentioned changes, you may add: Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Alice
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