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); +}
