On Tue, Aug 14, 2012 at 5:17 PM, Fengguang Wu <fengguang...@intel.com> wrote: > Rationals from Eric: > > So I just looked a little deeper and it appears architectures that do > not support atomic64_t are broken. > > The generic atomic64 support came in 2009 to support the perf subsystem > with the expectation that all architectures would implement atomic64 > support. > > Furthermore upon inspection of the kernel atomic64_t is used in a fair > number of places beyond the performance counters: > > block/blk-cgroup.c > drivers/acpi/apei/ > drivers/block/rbd.c > drivers/crypto/nx/nx.h > drivers/gpu/drm/radeon/radeon.h > drivers/infiniband/hw/ipath/ > drivers/infiniband/hw/qib/ > drivers/staging/octeon/ > fs/xfs/ > include/linux/perf_event.h > include/net/netfilter/nf_conntrack_acct.h > kernel/events/ > kernel/trace/ > net/mac80211/key.h > net/rds/ > > The block control group, infiniband, xfs, crypto, 802.11, netfilter. > Nothing quite so fundamental as fs/namespace.c but definitely in > multiplatform-code that should work, and is already broken on those > architecutres. > > Looking at the implementation of atomic64_add_return in lib/atomic64.c > the code looks as efficient as these kinds of things get. > > Which leads me to the conclusion that we need atomic64 support on all > architectures. > > CC: "Eric W. Biederman" <ebied...@xmission.com> > Signed-off-by: Fengguang Wu <fengguang...@intel.com>
Acked-by: Geert Uytterhoeven <ge...@linux-m68k.org> > --- > arch/mn10300/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > --- linux.orig/arch/mn10300/Kconfig 2012-08-03 15:36:21.391560778 +0800 > +++ linux/arch/mn10300/Kconfig 2012-08-14 22:53:14.751795832 +0800 > @@ -8,6 +8,7 @@ config MN10300 > select HAVE_ARCH_KGDB > select HAVE_NMI_WATCHDOG if MN10300_WD_TIMER > select GENERIC_CLOCKEVENTS > + select GENERIC_ATOMIC64 > > config AM33_2 > def_bool n Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/