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: sta...@vger.kernel.org
Signed-off-by: Arnd Bergmann <a...@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

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