From: Arnaldo Carvalho de Melo acme@redhat.com
[ 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 ‘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 Signed-off-by: Sasha Levin alexander.levin@verizon.com --- 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 @@ # define POISON_POINTER_DELTA 0 #endif
+#ifdef __cplusplus +#define LIST_POISON1 NULL +#define LIST_POISON2 NULL +#else /* * 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) +#endif
/********** include/linux/timer.h **********/ /*