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 ‘void list_del(list_head*)’:
/home/lizj/linux/tools/include/linux/poison.h:14:31: error: pointer of type ‘void *’ used in arithmetic [-Werror=pointer-arith]
# define POISON_POINTER_DELTA 0
^
/home/lizj/linux/tools/include/linux/poison.h:22:41: note: in expansion of macro ‘POISON_POINTER_DELTA’
#define LIST_POISON1 ((void *) 0x100 + POISON_POINTER_DELTA)
^
/home/lizj/linux/tools/include/linux/list.h:107:16: note: in expansion of macro ‘LIST_POISON1’
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 ‘void*’ to ‘list_head*’ [-fpermissive]
Reported-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Philip Li <philip.li@intel.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-m5ei2o0mjshucbr28baf5lqz@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
6ae8eefc6c