On Sat, 17 Mar 2007, Arnd Bergmann wrote:
> On Friday 16 March 2007 01:22:15 Davide Libenzi wrote:
> > +asmlinkage long compat_sys_signalfd(int ufd,
> > + const compat_sigset_t __user *sigmask,
> > + compat_size_t sigsetsize)
> > +{
> > + compat_sigset_t ss32;
> > + sigset_t tmp;
> > + sigset_t __user *ksigmask;
> > +
> > + if (sigsetsize != sizeof(compat_sigset_t))
> > + return -EINVAL;
> > + if (copy_from_user(&ss32, sigmask, sizeof(ss32)))
> > + return -EFAULT;
> > + sigset_from_compat(&tmp, &ss32);
> > + ksigmask = compat_alloc_user_space(sizeof(sigset_t));
> > + if (copy_to_user(ksigmask, &tmp, sizeof(sigset_t)))
> > + return -EFAULT;
> > +
> > + return sys_signalfd(ufd, ksigmask, sizeof(sigset_t));
> > +}
>
> Doing the compat_alloc_user_space() magic obviously makes the 32 bit
> emulation code less efficient. How about having a
>
> long do_signalfd(int ufd, const sigset_t *sigmask, size_t sigsetsize);
>
> that is called directly by both sys_signalfd and compat_sys_signalfd?
> Same obviously applies also to do_timerfd.
Hmm, copy_*_user (one or two moves) and compat_alloc_user_space are
pretty fast...
- Davide
