Quoting Richard Guy Briggs (rgb@xxxxxxxxxx):
> On 14/05/02, Serge E. Hallyn wrote:
> > Quoting Richard Guy Briggs (rgb@xxxxxxxxxx):
> >
> > Most of this looks reasonable, but I'm curious about something,
> >
> > > +/**
> > > + * ns_serial - compute a serial number for the namespace
> > > + *
> > > + * Compute a serial number for the namespace to uniquely identify it in
> > > + * audit records.
> > > + */
> > > +unsigned int ns_serial(void)
> > > +{
> > > + static DEFINE_SPINLOCK(serial_lock);
> > > + static unsigned int serial = 4; /* reserved for IPC, UTS, user, PID */
> > > +
> > > + unsigned long flags;
> > > + unsigned int ret;
> > > +
> > > + spin_lock_irqsave(&serial_lock, flags);
> > > + do {
> > > + ret = ++serial;
> > > + } while (unlikely(!ret));
> >
> > Why exactly are you doing this? Surely if serial is going to
> > wrap around we've got a bigger problem than just wanting go
> > bump one more time?
>
> Thanks for catching this.
> The code was templated off audit_serial() which tries to solve a
> different problem and rolling it is much more likely. I hadn't noticed
> that rollover protection. However, I *had* thought of making it a long
> (which would be the same size on 32-bit arches, but larger on 64-bit)
> since a 64-bit system is more likely to roll it out of sheer speed and
> resource availability. But perhaps a long long would be safer.
Sounds good, and perhaps a BUG_ON(!serial) for good measure.
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