Re: [PATCH] wifi: mac80211: fix unassigned variable access

[Johannes Berg <johannes@sipsolutions.net>]

On Tue, 2025-07-22 at 11:00 +0200, Antonio Quartulli wrote:
> > So I think if anything we should worry about the
> > 
> >                  if (time_is_after_jiffies(timeout) &&
> >                      time_after(timeout, latest_timeout))
> >                          latest_timeout = timeout;
> > 
> > comparison, but for that just unconditionally setting it to 0 is really
> > the wrong thing to do, since it means you compare to an arbitrary time
> > zero here?
> 
> We are looking for the maximum timeout, so using 0 (minimum possible 
> value) as base line should be what we want, no?
> 
> [note: I am assuming 0 is not a possible timeout value]

That assumption is wrong, in fact jiffies starts at a slightly negative
value (about 5 minutes?) so that a few minutes after boot the time goes
to the perfectly valid value zero. And on HZ=1000 32-bit systems, this
situation of course reappears every ~49.7 days.
> 
> Alternatively, we can just skip evaluating time_after() when 
> latest_timeout is 0.

But then we'd also have to set it to 1 if a timeout value is actually 0.

johannes