While reading through the sysvipc implementation, I noticed that the n32
semctl/shmctl/msgctl system calls behave differently based on whether
o32 support is enabled or not: Without o32, the IPC_64 flag passed by
user space is rejected but calls without that flag get IPC_64 behavior.

As far as I can tell, this was inadvertently changed by a cleanup patch
but never noticed by anyone, possibly nobody has tried using sysvipc
on n32 after linux-3.19.

Change it back to the old behavior now.

Fixes: 78aaf956ba3a ("MIPS: Compat: Fix build error if CONFIG_MIPS32_COMPAT but no compat ABI.")
Cc: stable@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
As stated above, this was only found by inspection, the patch is not
tested. Please review accordingly.
---
 arch/mips/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 787290781b8c..0d14f51d0002 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig

@@ -3155,6 +3155,7 @@ config MIPS32_O32
 config MIPS32_N32
 	bool "Kernel support for n32 binaries"
 	depends on 64BIT
+	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 	select COMPAT
 	select MIPS32_COMPAT
 	select SYSVIPC_COMPAT if SYSVIPC

-- 
2.20.0