Re: [PATCH] Microoptimization of lib/poll.c

[Paolo Bonzini]

> >  #ifdef _SC_OPEN_MAX
> > -  if (nfd > sysconf (_SC_OPEN_MAX))
> > +  static int sc_open_max = -1;
> > +
> > +  if (nfd < 0
> > +      || (nfd > sc_open_max
> > +          && (sc_open_max != -1
> > +             || nfd > (sc_open_max = sysconf (_SC_OPEN_MAX)))))
>
> Doesn't this make poll non-reentrant?
> Are there systems where assigning to an int is not atomic?

I don't think so, and gnulib's gt_TYPE_SIG_ATOMIC_T defines sig_atomic_t 
as int if there is none provided by the system.  I can make sc_open_max 
a sig_atomic_t if we care about it.

Paolo