[PATCH AUTOSEL for 4.14 47/51] tools include: Do not use poison with C++

From: alexander . levin
Date: Wed Nov 22 2017 - 17:44:15 EST

From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

[ Upstream commit 6ae8eefc6c8fe050f057781b70a83262eb0a61ee ]

LIST_POISON[12] are used to initialize list_head and hlist_node
pointers, and do void pointer arithmetic, which C++ doesn't like, so, to
avoid drifting from the kernel by introducing some HLIST_POISON to do
away with void pointer math, just make those poisoned pointers be NULL
when building it with a C++ compiler.

Noticed with:

$ make LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
CXX util/c++/clang.o
CXX util/c++/clang-test.o
In file included from /home/lizj/linux/tools/include/linux/list.h:5:0,
from /home/lizj/linux/tools/perf/util/namespaces.h:13,
from /home/lizj/linux/tools/perf/util/util.h:15,
from /home/lizj/linux/tools/perf/util/util-cxx.h:20,
from util/c++/clang-c.h:5,
from util/c++/clang-test.cpp:2:
/home/lizj/linux/tools/include/linux/list.h: In function âvoid list_del(list_head*)â:
/home/lizj/linux/tools/include/linux/poison.h:14:31: error: pointer of type âvoid *â used in arithmetic [-Werror=pointer-arith]
/home/lizj/linux/tools/include/linux/poison.h:22:41: note: in expansion of macro âPOISON_POINTER_DELTAâ
#define LIST_POISON1 ((void *) 0x100 + POISON_POINTER_DELTA)
/home/lizj/linux/tools/include/linux/list.h:107:16: note: in expansion of macro âLIST_POISON1â
entry->next = LIST_POISON1;
In file included from /home/lizj/linux/tools/perf/util/namespaces.h:13:0,
from /home/lizj/linux/tools/perf/util/util.h:15,
from /home/lizj/linux/tools/perf/util/util-cxx.h:20,
from util/c++/clang-c.h:5,
from util/c++/clang-test.cpp:2:
/home/lizj/linux/tools/include/linux/list.h:107:14: error: invalid conversion from âvoid*â to âlist_head*â [-fpermissive]

Reported-by: Li Zhijian <lizhijian@xxxxxxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Philip Li <philip.li@xxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-m5ei2o0mjshucbr28baf5lqz@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
tools/include/linux/poison.h | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/tools/include/linux/poison.h b/tools/include/linux/poison.h
index 4bf6777a8a03..9fdcd3eaac3b 100644
--- a/tools/include/linux/poison.h
+++ b/tools/include/linux/poison.h
@@ -15,6 +15,10 @@

+#ifdef __cplusplus
* These are non-NULL pointers that will result in page faults
* under normal circumstances, used to verify that nobody uses
@@ -22,6 +26,7 @@
#define LIST_POISON1 ((void *) 0x100 + POISON_POINTER_DELTA)
#define LIST_POISON2 ((void *) 0x200 + POISON_POINTER_DELTA)

/********** include/linux/timer.h **********/