futex_atomic_cmpxchg_inatomic() does not work on UML because
it triggers a copy_from_user() in kernel context.
On UML copy_from_user() can only be used if the kernel was called
by a real user space process such that UML can use ptrace()
to fetch the value.
Reported-by: Miklos Szeredi <mik...@szeredi.hu>
Suggested-by: Geert Uytterhoeven <ge...@linux-m68k.org>
Signed-off-by: Richard Weinberger <rich...@nod.at>
---
arch/um/Kconfig.common | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/um/Kconfig.common b/arch/um/Kconfig.common
index 87bc868..d195a87 100644
--- a/arch/um/Kconfig.common
+++ b/arch/um/Kconfig.common
@@ -3,6 +3,7 @@ config UML
default y
select HAVE_ARCH_AUDITSYSCALL
select HAVE_UID16
+ select HAVE_FUTEX_CMPXCHG if FUTEX
select GENERIC_IRQ_SHOW
select GENERIC_CPU_DEVICES
select GENERIC_IO
--
2.1.0
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