On Thu, Dec 10, 2020 at 5:59 PM Willem de Bruijn <willemdebruijn.kernel@xxxxxxxxx> wrote: > > On Thu, Dec 10, 2020 at 3:34 PM Arnd Bergmann <arnd@xxxxxxxxxx> wrote: > > > > On Thu, Dec 10, 2020 at 6:33 PM Willem de Bruijn > > <willemdebruijn.kernel@xxxxxxxxx> wrote: > > > On Sat, Nov 21, 2020 at 4:27 AM Arnd Bergmann <arnd@xxxxxxxxxx> wrote: > > > > On Fri, Nov 20, 2020 at 11:28 PM Willem de Bruijn <willemdebruijn.kernel@xxxxxxxxx> wrote: > > > > I would imagine this can be done like the way I proposed > > > > for get_bitmap() in sys_migrate_pages: > > > > > > > > https://lore.kernel.org/lkml/20201102123151.2860165-4-arnd@xxxxxxxxxx/ > > > > > > Coming back to this. Current patchset includes new select and poll > > > selftests to verify the changes. I need to send a small kselftest > > > patch for that first. > > > > > > Assuming there's no time pressure, I will finish up and send the main > > > changes after the merge window, for the next release then. > > > > > > Current state against linux-next at > > > https://github.com/wdebruij/linux-next-mirror/tree/select-compat-1 > > > > Ok, sounds good to me. I've had a (very brief) look and have one > > suggestion: instead of open-coding the compat vs native mode > > in multiple places like > > > > if (!in_compat_syscall()) > >  return copy_from_user(fdset, ufdset, FDS_BYTES(nr)) ? -EFAULT : 0; > > else > >  return compat_get_bitmap(fdset, ufdset, nr); > > > > maybe move this into a separate function and call that where needed. > > > > I've done this for the get_bitmap() function in my series at > > > > https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git/commit/?h=compat-alloc-user-space-7&id=b1b23ebb12b635654a2060df49455167a142c5d2 > > > > The definition is slightly differrent for cpumask, nodemask and fd_set, > > so we'd need to try out the best way to structure the code to end > > up with the most readable version, but it should be possible when > > there are only three callers (and duplicating the function would > > be the end of the world either) > > For fd_set there is only a single caller for each direction. Do you > prefer helpers even so? > > For sigmask, with three callers, something along the lines of this? > > @@ -1138,10 +1135,7 @@ static int do_ppoll(struct pollfd __user > *ufds, unsigned int nfds, > return -EINVAL; > } > > - if (!in_compat_syscall()) > - ret = set_user_sigmask(sigmask, sigsetsize); > - else > - ret = set_compat_user_sigmask(sigmask, sigsetsize); > + ret = set_maybe_compat_user_sigmask(sigmask, sigsetsize); > if (ret) > return ret; > > --- a/include/linux/compat.h > +++ b/include/linux/compat.h > @@ -942,6 +942,17 @@ static inline bool in_compat_syscall(void) { > return false; } > > +static inline int set_maybe_compat_user_sigmask(const void __user *sigmask, > + size_t sigsetsize) > +{ > +#if defined CONFIG_COMPAT > + if (unlikely(in_compat_syscall())) > + return set_compat_user_sigmask(sigmask, sigsetsize); > +#endif > + > + return set_user_sigmask(sigmask, sigsetsize); > +} set_user_sigmask is the only open-coded variant that is used more than once. Because it is used in both select.c and eventpoll.c, a helper would have to live in compat.h. This then needs a new dependency on sched_signal.h. So given that this is a simple branch, it might just make logic more complex, instead of less. I can add this change in a separate patch on top of the original three, to judge whether it is worthwhile.
