powerpc: fix EDEADLOCK redefinition error in uapi/asm/errno.h

commit 7de21e679e6a789f3729e8402bc440b623a28eae upstream.

A few archs like powerpc have different errno.h values for macros
EDEADLOCK and EDEADLK. In code including both libc and linux versions of
errno.h, this can result in multiple definitions of EDEADLOCK in the
include chain. Definitions to the same value (e.g. seen with mips) do
not raise warnings, but on powerpc there are redefinitions changing the
value, which raise warnings and errors (if using "-Werror").

Guard against these redefinitions to avoid build errors like the following,
first seen cross-compiling libbpf v5.8.9 for powerpc using GCC 8.4.0 with
musl 1.1.24:

  In file included from ../../arch/powerpc/include/uapi/asm/errno.h:5,
                   from ../../include/linux/err.h:8,
                   from libbpf.c:29:
  ../../include/uapi/asm-generic/errno.h:40: error: "EDEADLOCK" redefined [-Werror]
   #define EDEADLOCK EDEADLK

  In file included from toolchain-powerpc_8540_gcc-8.4.0_musl/include/errno.h:10,
                   from libbpf.c:26:
  toolchain-powerpc_8540_gcc-8.4.0_musl/include/bits/errno.h:58: note: this is the location of the previous definition
   #define EDEADLOCK       58

  cc1: all warnings being treated as errors

Cc: Stable <stable@vger.kernel.org>
Reported-by: Rosen Penev <rosenp@gmail.com>
Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200917135437.1238787-1-Tony.Ambardar@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/powerpc/include/uapi/asm/errno.h b/arch/powerpc/include/uapi/asm/errno.h
index e8b6b5f7de7c4b2548c6b2c39fee00f624d20036..5e8f42ff797fbd5dad0e22326c38558e08bca342 100644 (file)
--- a/arch/powerpc/include/uapi/asm/errno.h
+++ b/arch/powerpc/include/uapi/asm/errno.h
@@ -1,6 +1,7 @@
 #ifndef _ASM_POWERPC_ERRNO_H
 #define _ASM_POWERPC_ERRNO_H
 
+#undef EDEADLOCK
 #include <asm-generic/errno.h>
 
 #undef EDEADLOCK