Hi Jeff, On Tue, Jul 9, 2024 at 1:58 PM Jeff Layton <jlayton@xxxxxxxxxx> wrote: > I've been getting some of these warning emails from the KTR. I think > this is in reference to this patch, which adds a 64-bit try_cmpxchg in > the timestamp handling code: > > https://lore.kernel.org/linux-fsdevel/20240708-mgtime-v4-0-a0f3c6fb57f3@xxxxxxxxxx/ > > On m68k, there is a prototype for __invalid_cmpxchg_size, but no actual > function, AFAICT. Should that be defined somewhere, or is this a > deliberate way to force a build break in this case? It's a deliberate way to break the build. > More to the point though: do I need to do anything special for m86k > here (or for other arches that can't do a native 64-bit cmpxchg)? 64-bit cmpxchg() is only guaranteed to exist on 64-bit platforms. See also https://elixir.bootlin.com/linux/latest/source/include/asm-generic/cmpxchg.h#L62 I think you can use arch_cmpxchg64(), though. > ---------- Forwarded message ---------- > From: kernel test robot <lkp@xxxxxxxxx> > m68k-linux-ld: fs/inode.o: in function `inode_set_ctime_current': > >> inode.c:(.text+0x167a): undefined reference to `__invalid_cmpxchg_size' Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
