Re: [PATCH v2] tools include: define READ_ONCE/WRITE_ONCE for C++

2018-04-04 Thread Sandipan Das 
Hi,

On 11/30/2017 07:06 AM, Li Zhijian wrote:
> since 6aa7de0, we failed to build perf with C++(clang)
> to fix the following compile errors
> --
> lizhijian@haswell-OptiPlex-9020:~/lkp/linux/tools/perf$ make 
> LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
> ...
>   CC   util/probe-finder.o
> In file included from /home/lizj/linux/tools/perf/util/util.h:13:0,
>  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/asm/../../arch/x86/include/asm/atomic.h: In 
> function ‘int atomic_read(const atomic_t*)’:
> /home/lizj/linux/tools/include/linux/compiler.h:157:45: error: use of deleted 
> function ‘atomic_read(const atomic_t*)()’
>   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
> __u.__c, sizeof(x)); __u.__val; })
>  ^
> /home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
> note: in expansion of macro ‘READ_ONCE’
>   return READ_ONCE((v)->counter);
>  ^
> /home/lizj/linux/tools/include/linux/compiler.h:157:11: note: 
> ‘atomic_read(const atomic_t*)()’ is 
> implicitly deleted because the default definition would be ill-formed:
>   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
> __u.__c, sizeof(x)); __u.__val; })
>^
> /home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
> note: in expansion of macro ‘READ_ONCE’
>   return READ_ONCE((v)->counter);
>  ^
> /home/lizj/linux/tools/include/linux/compiler.h:157:11: error: uninitialized 
> const member in ‘union atomic_read(const atomic_t*)::’
>   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
> __u.__c, sizeof(x)); __u.__val; })
>^
> /home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
> note: in expansion of macro ‘READ_ONCE’
>   return READ_ONCE((v)->counter);
>  ^
> /home/lizj/linux/tools/include/linux/compiler.h:157:23: note: ‘const int 
> atomic_read(const atomic_t*)__val’ should be initialized
>   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
> __u.__c, sizeof(x)); __u.__val; })
>^
> /home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
> note: in expansion of macro ‘READ_ONCE’
>   return READ_ONCE((v)->counter);
>  ^
>   LD   tests/perf-in.o
> ...
> --
> 

I ran into the same problems while building perf with clang support.
If the solution proposed here is acceptable, can someone please pick
up this patch?

--
With Regards,
Sandipan

Re: [PATCH v2] tools include: define READ_ONCE/WRITE_ONCE for C++

2018-04-04 Thread Sandipan Das 
Hi,

On 11/30/2017 07:06 AM, Li Zhijian wrote:
> since 6aa7de0, we failed to build perf with C++(clang)
> to fix the following compile errors
> --
> lizhijian@haswell-OptiPlex-9020:~/lkp/linux/tools/perf$ make 
> LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
> ...
>   CC   util/probe-finder.o
> In file included from /home/lizj/linux/tools/perf/util/util.h:13:0,
>  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/asm/../../arch/x86/include/asm/atomic.h: In 
> function ‘int atomic_read(const atomic_t*)’:
> /home/lizj/linux/tools/include/linux/compiler.h:157:45: error: use of deleted 
> function ‘atomic_read(const atomic_t*)()’
>   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
> __u.__c, sizeof(x)); __u.__val; })
>  ^
> /home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
> note: in expansion of macro ‘READ_ONCE’
>   return READ_ONCE((v)->counter);
>  ^
> /home/lizj/linux/tools/include/linux/compiler.h:157:11: note: 
> ‘atomic_read(const atomic_t*)()’ is 
> implicitly deleted because the default definition would be ill-formed:
>   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
> __u.__c, sizeof(x)); __u.__val; })
>^
> /home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
> note: in expansion of macro ‘READ_ONCE’
>   return READ_ONCE((v)->counter);
>  ^
> /home/lizj/linux/tools/include/linux/compiler.h:157:11: error: uninitialized 
> const member in ‘union atomic_read(const atomic_t*)::’
>   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
> __u.__c, sizeof(x)); __u.__val; })
>^
> /home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
> note: in expansion of macro ‘READ_ONCE’
>   return READ_ONCE((v)->counter);
>  ^
> /home/lizj/linux/tools/include/linux/compiler.h:157:23: note: ‘const int 
> atomic_read(const atomic_t*)__val’ should be initialized
>   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
> __u.__c, sizeof(x)); __u.__val; })
>^
> /home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
> note: in expansion of macro ‘READ_ONCE’
>   return READ_ONCE((v)->counter);
>  ^
>   LD   tests/perf-in.o
> ...
> --
> 

I ran into the same problems while building perf with clang support.
If the solution proposed here is acceptable, can someone please pick
up this patch?

--
With Regards,
Sandipan

tools include: define READ_ONCE/WRITE_ONCE for C++

2018-04-03 Thread Sandipan Das 
From: Li Zhijian 

since 6aa7de0, we failed to build perf with C++(clang)
to fix the following compile errors
--
lizhijian@haswell-OptiPlex-9020:~/lkp/linux/tools/perf$ make 
LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
...
  CC   util/probe-finder.o
In file included from /home/lizj/linux/tools/perf/util/util.h:13:0,
 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/asm/../../arch/x86/include/asm/atomic.h: In 
function ‘int atomic_read(const atomic_t*)’:
/home/lizj/linux/tools/include/linux/compiler.h:157:45: error: use of deleted 
function ‘atomic_read(const atomic_t*)()’
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
 ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: note: 
‘atomic_read(const atomic_t*)()’ is 
implicitly deleted because the default definition would be ill-formed:
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: error: uninitialized 
const member in ‘union atomic_read(const atomic_t*)::’
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:23: note: ‘const int 
atomic_read(const atomic_t*)__val’ should be initialized
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
  LD   tests/perf-in.o
...
--

Signed-off-by: Li Zhijian 
---
 tools/include/linux/compiler.h | 5 +
 1 file changed, 5 insertions(+)

diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 07fd03c..e4c8a0d 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -86,6 +86,10 @@
 
 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
 
+#ifdef __cplusplus
+#define READ_ONCE(x) ACCESS_ONCE(x)
+#define WRITE_ONCE(x, val) ACCESS_ONCE(x) = val
+#else
 #include 
 
 /*
@@ -160,6 +164,7 @@ static __always_inline void __write_once_size(volatile void 
*p, void *res, int s
 #define WRITE_ONCE(x, val) \
({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; 
__write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
 
+#endif /* __cplusplus */
 
 #ifndef __fallthrough
 # define __fallthrough

tools include: define READ_ONCE/WRITE_ONCE for C++

2018-04-03 Thread Sandipan Das 
From: Li Zhijian 

since 6aa7de0, we failed to build perf with C++(clang)
to fix the following compile errors
--
lizhijian@haswell-OptiPlex-9020:~/lkp/linux/tools/perf$ make 
LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
...
  CC   util/probe-finder.o
In file included from /home/lizj/linux/tools/perf/util/util.h:13:0,
 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/asm/../../arch/x86/include/asm/atomic.h: In 
function ‘int atomic_read(const atomic_t*)’:
/home/lizj/linux/tools/include/linux/compiler.h:157:45: error: use of deleted 
function ‘atomic_read(const atomic_t*)()’
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
 ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: note: 
‘atomic_read(const atomic_t*)()’ is 
implicitly deleted because the default definition would be ill-formed:
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: error: uninitialized 
const member in ‘union atomic_read(const atomic_t*)::’
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:23: note: ‘const int 
atomic_read(const atomic_t*)__val’ should be initialized
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
  LD   tests/perf-in.o
...
--

Signed-off-by: Li Zhijian 
---
 tools/include/linux/compiler.h | 5 +
 1 file changed, 5 insertions(+)

diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 07fd03c..e4c8a0d 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -86,6 +86,10 @@
 
 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
 
+#ifdef __cplusplus
+#define READ_ONCE(x) ACCESS_ONCE(x)
+#define WRITE_ONCE(x, val) ACCESS_ONCE(x) = val
+#else
 #include 
 
 /*
@@ -160,6 +164,7 @@ static __always_inline void __write_once_size(volatile void 
*p, void *res, int s
 #define WRITE_ONCE(x, val) \
({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; 
__write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
 
+#endif /* __cplusplus */
 
 #ifndef __fallthrough
 # define __fallthrough

Re: [PATCH v2] tools include: define READ_ONCE/WRITE_ONCE for C++

2017-12-14 Thread Li Zhijian 

ping


On 11/30/2017 09:36 AM, Li Zhijian wrote:

since 6aa7de0, we failed to build perf with C++(clang)
to fix the following compile errors
--
lizhijian@haswell-OptiPlex-9020:~/lkp/linux/tools/perf$ make 
LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
...
   CC   util/probe-finder.o
In file included from /home/lizj/linux/tools/perf/util/util.h:13:0,
  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/asm/../../arch/x86/include/asm/atomic.h: In 
function ‘int atomic_read(const atomic_t*)’:
/home/lizj/linux/tools/include/linux/compiler.h:157:45: error: use of deleted function 
‘atomic_read(const atomic_t*)()’
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
  ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: note: ‘atomic_read(const 
atomic_t*)()’ is implicitly deleted because 
the default definition would be ill-formed:
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: error: uninitialized const 
member in ‘union atomic_read(const atomic_t*)::’
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:23: note: ‘const int 
atomic_read(const atomic_t*)__val’ should be initialized
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
   LD   tests/perf-in.o
...
--

Signed-off-by: Li Zhijian 
---
  tools/include/linux/compiler.h | 5 +
  1 file changed, 5 insertions(+)

diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 07fd03c..d6675c5 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -86,6 +86,10 @@
  
  #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
  
+#ifdef __cplusplus

+#define READ_ONCE(x) (*(volatile typeof(x) *)&(x))
+#define WRITE_ONCE(x, val) (*(volatile typeof(x) *)&(x)) = (val)
+#else
  #include 
  
  /*

@@ -160,6 +164,7 @@ static __always_inline void __write_once_size(volatile void 
*p, void *res, int s
  #define WRITE_ONCE(x, val) \
({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; 
__write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
  
+#endif /* __cplusplus */
  
  #ifndef __fallthrough

  # define __fallthrough


--
Best regards.
Li Zhijian (8528)

Re: [PATCH v2] tools include: define READ_ONCE/WRITE_ONCE for C++

2017-12-14 Thread Li Zhijian 

ping


On 11/30/2017 09:36 AM, Li Zhijian wrote:

since 6aa7de0, we failed to build perf with C++(clang)
to fix the following compile errors
--
lizhijian@haswell-OptiPlex-9020:~/lkp/linux/tools/perf$ make 
LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
...
   CC   util/probe-finder.o
In file included from /home/lizj/linux/tools/perf/util/util.h:13:0,
  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/asm/../../arch/x86/include/asm/atomic.h: In 
function ‘int atomic_read(const atomic_t*)’:
/home/lizj/linux/tools/include/linux/compiler.h:157:45: error: use of deleted function 
‘atomic_read(const atomic_t*)()’
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
  ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: note: ‘atomic_read(const 
atomic_t*)()’ is implicitly deleted because 
the default definition would be ill-formed:
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: error: uninitialized const 
member in ‘union atomic_read(const atomic_t*)::’
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:23: note: ‘const int 
atomic_read(const atomic_t*)__val’ should be initialized
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
   LD   tests/perf-in.o
...
--

Signed-off-by: Li Zhijian 
---
  tools/include/linux/compiler.h | 5 +
  1 file changed, 5 insertions(+)

diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 07fd03c..d6675c5 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -86,6 +86,10 @@
  
  #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
  
+#ifdef __cplusplus

+#define READ_ONCE(x) (*(volatile typeof(x) *)&(x))
+#define WRITE_ONCE(x, val) (*(volatile typeof(x) *)&(x)) = (val)
+#else
  #include 
  
  /*

@@ -160,6 +164,7 @@ static __always_inline void __write_once_size(volatile void 
*p, void *res, int s
  #define WRITE_ONCE(x, val) \
({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; 
__write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
  
+#endif /* __cplusplus */
  
  #ifndef __fallthrough

  # define __fallthrough


--
Best regards.
Li Zhijian (8528)

[PATCH v2] tools include: define READ_ONCE/WRITE_ONCE for C++

2017-11-29 Thread Li Zhijian 
since 6aa7de0, we failed to build perf with C++(clang)
to fix the following compile errors
--
lizhijian@haswell-OptiPlex-9020:~/lkp/linux/tools/perf$ make 
LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
...
  CC   util/probe-finder.o
In file included from /home/lizj/linux/tools/perf/util/util.h:13:0,
 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/asm/../../arch/x86/include/asm/atomic.h: In 
function ‘int atomic_read(const atomic_t*)’:
/home/lizj/linux/tools/include/linux/compiler.h:157:45: error: use of deleted 
function ‘atomic_read(const atomic_t*)()’
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
 ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: note: 
‘atomic_read(const atomic_t*)()’ is 
implicitly deleted because the default definition would be ill-formed:
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: error: uninitialized 
const member in ‘union atomic_read(const atomic_t*)::’
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:23: note: ‘const int 
atomic_read(const atomic_t*)__val’ should be initialized
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
  LD   tests/perf-in.o
...
--

Signed-off-by: Li Zhijian 
---
 tools/include/linux/compiler.h | 5 +
 1 file changed, 5 insertions(+)

diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 07fd03c..d6675c5 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -86,6 +86,10 @@
 
 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
 
+#ifdef __cplusplus
+#define READ_ONCE(x) (*(volatile typeof(x) *)&(x))
+#define WRITE_ONCE(x, val) (*(volatile typeof(x) *)&(x)) = (val)
+#else
 #include 
 
 /*
@@ -160,6 +164,7 @@ static __always_inline void __write_once_size(volatile void 
*p, void *res, int s
 #define WRITE_ONCE(x, val) \
({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; 
__write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
 
+#endif /* __cplusplus */
 
 #ifndef __fallthrough
 # define __fallthrough
-- 
2.7.4

[PATCH v2] tools include: define READ_ONCE/WRITE_ONCE for C++

2017-11-29 Thread Li Zhijian 
since 6aa7de0, we failed to build perf with C++(clang)
to fix the following compile errors
--
lizhijian@haswell-OptiPlex-9020:~/lkp/linux/tools/perf$ make 
LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
...
  CC   util/probe-finder.o
In file included from /home/lizj/linux/tools/perf/util/util.h:13:0,
 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/asm/../../arch/x86/include/asm/atomic.h: In 
function ‘int atomic_read(const atomic_t*)’:
/home/lizj/linux/tools/include/linux/compiler.h:157:45: error: use of deleted 
function ‘atomic_read(const atomic_t*)()’
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
 ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: note: 
‘atomic_read(const atomic_t*)()’ is 
implicitly deleted because the default definition would be ill-formed:
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: error: uninitialized 
const member in ‘union atomic_read(const atomic_t*)::’
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:23: note: ‘const int 
atomic_read(const atomic_t*)__val’ should be initialized
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
  LD   tests/perf-in.o
...
--

Signed-off-by: Li Zhijian 
---
 tools/include/linux/compiler.h | 5 +
 1 file changed, 5 insertions(+)

diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 07fd03c..d6675c5 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -86,6 +86,10 @@
 
 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
 
+#ifdef __cplusplus
+#define READ_ONCE(x) (*(volatile typeof(x) *)&(x))
+#define WRITE_ONCE(x, val) (*(volatile typeof(x) *)&(x)) = (val)
+#else
 #include 
 
 /*
@@ -160,6 +164,7 @@ static __always_inline void __write_once_size(volatile void 
*p, void *res, int s
 #define WRITE_ONCE(x, val) \
({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; 
__write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
 
+#endif /* __cplusplus */
 
 #ifndef __fallthrough
 # define __fallthrough
-- 
2.7.4

Re: [PATCH] tools include: define READ_ONCE/WRITE_ONCE for C++

2017-11-28 Thread Li Zhijian 


On 11/28/2017 07:30 PM, Mark Rutland wrote:

Hi,

[Fixed acme's address and added more Ccs]

thanks




On Tue, Nov 28, 2017 at 02:13:42PM +0800, Li Zhijian wrote:

since 6aa7de0, we failed to build perf with C++(clang)
to fix the following compile errors

Sorry about this.

With llvm-config and libclang from the LLVM 5.0.0 release, I can
reproduce this.


--
lizhijian@haswell-OptiPlex-9020:~/lkp/linux/tools/perf$ make 
LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
...
   CC   util/probe-finder.o
In file included from /home/lizj/linux/tools/perf/util/util.h:13:0,
  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/asm/../../arch/x86/include/asm/atomic.h: In 
function ‘int atomic_read(const atomic_t*)’:
/home/lizj/linux/tools/include/linux/compiler.h:157:45: error: use of deleted function 
‘atomic_read(const atomic_t*)()’
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
  ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: note: ‘atomic_read(const 
atomic_t*)()’ is implicitly deleted because 
the default definition would be ill-formed:
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: error: uninitialized const 
member in ‘union atomic_read(const atomic_t*)::’
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:23: note: ‘const int 
atomic_read(const atomic_t*)__val’ should be initialized
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
   LD   tests/perf-in.o

So IIUC, g++ doesn't like the union aliasing trick that we use here, and
doesn't believe that __val has been initialised.

I haven't found a way around that yet. Ideally we'd just have a
non-const temporary (and a __builtin_memcpy) rather than a union, but I
can't find a way to strip const from typeof() prior to c++11.


...
--

Signed-off-by: Li Zhijian 
---
  tools/include/linux/compiler.h | 5 +
  1 file changed, 5 insertions(+)

diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 07fd03c..e4c8a0d 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -86,6 +86,10 @@
  
  #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
  
+#ifdef __cplusplus

+#define READ_ONCE(x) ACCESS_ONCE(x)
+#define WRITE_ONCE(x, val) ACCESS_ONCE(x) = val
+#else
  #include 

This is somewhat unfortunate, since we want to get rid of ACCESS_ONCE().


Got it




I'll see if I can come up with something to make the existing
{READ,WRITE}_ONCE() work, so that we can avoid issues with non-scalar
types.


That's great if we can bring up the existing code.


Thanks
Zhijian



Otherwise, could we please make these:

#define READ_ONCE(x)(*(volatile typeof(x) *)&(x))
#define WRITE_ONCE(x)   (*(volatile typeof(x) *)&(x)) = (val)

Thanks,
Mark.


  /*
@@ -160,6 +164,7 @@ static __always_inline void __write_once_size(volatile void 
*p, void *res, int s
  #define WRITE_ONCE(x, val) \
({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; 
__write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
  
+#endif /* __cplusplus */
  
  #ifndef __fallthrough

  # define __fallthrough
--
2.7.4

Re: [PATCH] tools include: define READ_ONCE/WRITE_ONCE for C++

2017-11-28 Thread Li Zhijian 


On 11/28/2017 07:30 PM, Mark Rutland wrote:

Hi,

[Fixed acme's address and added more Ccs]

thanks




On Tue, Nov 28, 2017 at 02:13:42PM +0800, Li Zhijian wrote:

since 6aa7de0, we failed to build perf with C++(clang)
to fix the following compile errors

Sorry about this.

With llvm-config and libclang from the LLVM 5.0.0 release, I can
reproduce this.


--
lizhijian@haswell-OptiPlex-9020:~/lkp/linux/tools/perf$ make 
LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
...
   CC   util/probe-finder.o
In file included from /home/lizj/linux/tools/perf/util/util.h:13:0,
  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/asm/../../arch/x86/include/asm/atomic.h: In 
function ‘int atomic_read(const atomic_t*)’:
/home/lizj/linux/tools/include/linux/compiler.h:157:45: error: use of deleted function 
‘atomic_read(const atomic_t*)()’
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
  ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: note: ‘atomic_read(const 
atomic_t*)()’ is implicitly deleted because 
the default definition would be ill-formed:
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: error: uninitialized const 
member in ‘union atomic_read(const atomic_t*)::’
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:23: note: ‘const int 
atomic_read(const atomic_t*)__val’ should be initialized
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
   LD   tests/perf-in.o

So IIUC, g++ doesn't like the union aliasing trick that we use here, and
doesn't believe that __val has been initialised.

I haven't found a way around that yet. Ideally we'd just have a
non-const temporary (and a __builtin_memcpy) rather than a union, but I
can't find a way to strip const from typeof() prior to c++11.


...
--

Signed-off-by: Li Zhijian 
---
  tools/include/linux/compiler.h | 5 +
  1 file changed, 5 insertions(+)

diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 07fd03c..e4c8a0d 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -86,6 +86,10 @@
  
  #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
  
+#ifdef __cplusplus

+#define READ_ONCE(x) ACCESS_ONCE(x)
+#define WRITE_ONCE(x, val) ACCESS_ONCE(x) = val
+#else
  #include 

This is somewhat unfortunate, since we want to get rid of ACCESS_ONCE().


Got it




I'll see if I can come up with something to make the existing
{READ,WRITE}_ONCE() work, so that we can avoid issues with non-scalar
types.


That's great if we can bring up the existing code.


Thanks
Zhijian



Otherwise, could we please make these:

#define READ_ONCE(x)(*(volatile typeof(x) *)&(x))
#define WRITE_ONCE(x)   (*(volatile typeof(x) *)&(x)) = (val)

Thanks,
Mark.


  /*
@@ -160,6 +164,7 @@ static __always_inline void __write_once_size(volatile void 
*p, void *res, int s
  #define WRITE_ONCE(x, val) \
({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; 
__write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
  
+#endif /* __cplusplus */
  
  #ifndef __fallthrough

  # define __fallthrough
--
2.7.4

Re: [PATCH] tools include: define READ_ONCE/WRITE_ONCE for C++

2017-11-28 Thread Mark Rutland 
Hi,

[Fixed acme's address and added more Ccs]

On Tue, Nov 28, 2017 at 02:13:42PM +0800, Li Zhijian wrote:
> since 6aa7de0, we failed to build perf with C++(clang)
> to fix the following compile errors

Sorry about this.

With llvm-config and libclang from the LLVM 5.0.0 release, I can
reproduce this.

> --
> lizhijian@haswell-OptiPlex-9020:~/lkp/linux/tools/perf$ make 
> LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
> ...
>   CC   util/probe-finder.o
> In file included from /home/lizj/linux/tools/perf/util/util.h:13:0,
>  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/asm/../../arch/x86/include/asm/atomic.h: In 
> function ‘int atomic_read(const atomic_t*)’:
> /home/lizj/linux/tools/include/linux/compiler.h:157:45: error: use of deleted 
> function ‘atomic_read(const atomic_t*)()’
>   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
> __u.__c, sizeof(x)); __u.__val; })
>  ^
> /home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
> note: in expansion of macro ‘READ_ONCE’
>   return READ_ONCE((v)->counter);
>  ^
> /home/lizj/linux/tools/include/linux/compiler.h:157:11: note: 
> ‘atomic_read(const atomic_t*)()’ is 
> implicitly deleted because the default definition would be ill-formed:
>   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
> __u.__c, sizeof(x)); __u.__val; })
>^
> /home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
> note: in expansion of macro ‘READ_ONCE’
>   return READ_ONCE((v)->counter);
>  ^
> /home/lizj/linux/tools/include/linux/compiler.h:157:11: error: uninitialized 
> const member in ‘union atomic_read(const atomic_t*)::’
>   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
> __u.__c, sizeof(x)); __u.__val; })
>^
> /home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
> note: in expansion of macro ‘READ_ONCE’
>   return READ_ONCE((v)->counter);
>  ^
> /home/lizj/linux/tools/include/linux/compiler.h:157:23: note: ‘const int 
> atomic_read(const atomic_t*)__val’ should be initialized
>   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
> __u.__c, sizeof(x)); __u.__val; })
>^
> /home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
> note: in expansion of macro ‘READ_ONCE’
>   return READ_ONCE((v)->counter);
>  ^
>   LD   tests/perf-in.o

So IIUC, g++ doesn't like the union aliasing trick that we use here, and
doesn't believe that __val has been initialised.

I haven't found a way around that yet. Ideally we'd just have a
non-const temporary (and a __builtin_memcpy) rather than a union, but I
can't find a way to strip const from typeof() prior to c++11.

> ...
> --
> 
> Signed-off-by: Li Zhijian 
> ---
>  tools/include/linux/compiler.h | 5 +
>  1 file changed, 5 insertions(+)
> 
> diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
> index 07fd03c..e4c8a0d 100644
> --- a/tools/include/linux/compiler.h
> +++ b/tools/include/linux/compiler.h
> @@ -86,6 +86,10 @@
>  
>  #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
>  
> +#ifdef __cplusplus
> +#define READ_ONCE(x) ACCESS_ONCE(x)
> +#define WRITE_ONCE(x, val) ACCESS_ONCE(x) = val
> +#else
>  #include 

This is somewhat unfortunate, since we want to get rid of ACCESS_ONCE().

I'll see if I can come up with something to make the existing
{READ,WRITE}_ONCE() work, so that we can avoid issues with non-scalar
types.

Otherwise, could we please make these:

#define READ_ONCE(x)(*(volatile typeof(x) *)&(x))
#define WRITE_ONCE(x)   (*(volatile typeof(x) *)&(x)) = (val)

Thanks,
Mark.

>  /*
> @@ -160,6 +164,7 @@ static __always_inline void __write_once_size(volatile 
> void *p, void *res, int s
>  #define WRITE_ONCE(x, val) \
>   ({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; 
> __write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
>  
> +#endif /* __cplusplus */
>  
>  #ifndef __fallthrough
>  # define __fallthrough
> -- 
> 2.7.4
>

Re: [PATCH] tools include: define READ_ONCE/WRITE_ONCE for C++

2017-11-28 Thread Mark Rutland 
Hi,

[Fixed acme's address and added more Ccs]

On Tue, Nov 28, 2017 at 02:13:42PM +0800, Li Zhijian wrote:
> since 6aa7de0, we failed to build perf with C++(clang)
> to fix the following compile errors

Sorry about this.

With llvm-config and libclang from the LLVM 5.0.0 release, I can
reproduce this.

> --
> lizhijian@haswell-OptiPlex-9020:~/lkp/linux/tools/perf$ make 
> LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
> ...
>   CC   util/probe-finder.o
> In file included from /home/lizj/linux/tools/perf/util/util.h:13:0,
>  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/asm/../../arch/x86/include/asm/atomic.h: In 
> function ‘int atomic_read(const atomic_t*)’:
> /home/lizj/linux/tools/include/linux/compiler.h:157:45: error: use of deleted 
> function ‘atomic_read(const atomic_t*)()’
>   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
> __u.__c, sizeof(x)); __u.__val; })
>  ^
> /home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
> note: in expansion of macro ‘READ_ONCE’
>   return READ_ONCE((v)->counter);
>  ^
> /home/lizj/linux/tools/include/linux/compiler.h:157:11: note: 
> ‘atomic_read(const atomic_t*)()’ is 
> implicitly deleted because the default definition would be ill-formed:
>   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
> __u.__c, sizeof(x)); __u.__val; })
>^
> /home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
> note: in expansion of macro ‘READ_ONCE’
>   return READ_ONCE((v)->counter);
>  ^
> /home/lizj/linux/tools/include/linux/compiler.h:157:11: error: uninitialized 
> const member in ‘union atomic_read(const atomic_t*)::’
>   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
> __u.__c, sizeof(x)); __u.__val; })
>^
> /home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
> note: in expansion of macro ‘READ_ONCE’
>   return READ_ONCE((v)->counter);
>  ^
> /home/lizj/linux/tools/include/linux/compiler.h:157:23: note: ‘const int 
> atomic_read(const atomic_t*)__val’ should be initialized
>   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
> __u.__c, sizeof(x)); __u.__val; })
>^
> /home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
> note: in expansion of macro ‘READ_ONCE’
>   return READ_ONCE((v)->counter);
>  ^
>   LD   tests/perf-in.o

So IIUC, g++ doesn't like the union aliasing trick that we use here, and
doesn't believe that __val has been initialised.

I haven't found a way around that yet. Ideally we'd just have a
non-const temporary (and a __builtin_memcpy) rather than a union, but I
can't find a way to strip const from typeof() prior to c++11.

> ...
> --
> 
> Signed-off-by: Li Zhijian 
> ---
>  tools/include/linux/compiler.h | 5 +
>  1 file changed, 5 insertions(+)
> 
> diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
> index 07fd03c..e4c8a0d 100644
> --- a/tools/include/linux/compiler.h
> +++ b/tools/include/linux/compiler.h
> @@ -86,6 +86,10 @@
>  
>  #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
>  
> +#ifdef __cplusplus
> +#define READ_ONCE(x) ACCESS_ONCE(x)
> +#define WRITE_ONCE(x, val) ACCESS_ONCE(x) = val
> +#else
>  #include 

This is somewhat unfortunate, since we want to get rid of ACCESS_ONCE().

I'll see if I can come up with something to make the existing
{READ,WRITE}_ONCE() work, so that we can avoid issues with non-scalar
types.

Otherwise, could we please make these:

#define READ_ONCE(x)(*(volatile typeof(x) *)&(x))
#define WRITE_ONCE(x)   (*(volatile typeof(x) *)&(x)) = (val)

Thanks,
Mark.

>  /*
> @@ -160,6 +164,7 @@ static __always_inline void __write_once_size(volatile 
> void *p, void *res, int s
>  #define WRITE_ONCE(x, val) \
>   ({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; 
> __write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
>  
> +#endif /* __cplusplus */
>  
>  #ifndef __fallthrough
>  # define __fallthrough
> -- 
> 2.7.4
>

Re: [PATCH] tools include: define READ_ONCE/WRITE_ONCE for C++

2017-11-27 Thread Li Zhijian 

add Arnaldo Carvalho de Melo 


On 11/28/2017 02:13 PM, Li Zhijian wrote:

since 6aa7de0, we failed to build perf with C++(clang)
to fix the following compile errors
--
lizhijian@haswell-OptiPlex-9020:~/lkp/linux/tools/perf$ make 
LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
...
   CC   util/probe-finder.o
In file included from /home/lizj/linux/tools/perf/util/util.h:13:0,
  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/asm/../../arch/x86/include/asm/atomic.h: In 
function ‘int atomic_read(const atomic_t*)’:
/home/lizj/linux/tools/include/linux/compiler.h:157:45: error: use of deleted function 
‘atomic_read(const atomic_t*)()’
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
  ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: note: ‘atomic_read(const 
atomic_t*)()’ is implicitly deleted because 
the default definition would be ill-formed:
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: error: uninitialized const 
member in ‘union atomic_read(const atomic_t*)::’
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:23: note: ‘const int 
atomic_read(const atomic_t*)__val’ should be initialized
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
   LD   tests/perf-in.o
...
--

Signed-off-by: Li Zhijian 
---
  tools/include/linux/compiler.h | 5 +
  1 file changed, 5 insertions(+)

diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 07fd03c..e4c8a0d 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -86,6 +86,10 @@
  
  #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
  
+#ifdef __cplusplus

+#define READ_ONCE(x) ACCESS_ONCE(x)
+#define WRITE_ONCE(x, val) ACCESS_ONCE(x) = val
+#else
  #include 
  
  /*

@@ -160,6 +164,7 @@ static __always_inline void __write_once_size(volatile void 
*p, void *res, int s
  #define WRITE_ONCE(x, val) \
({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; 
__write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
  
+#endif /* __cplusplus */
  
  #ifndef __fallthrough

  # define __fallthrough

Re: [PATCH] tools include: define READ_ONCE/WRITE_ONCE for C++

2017-11-27 Thread Li Zhijian 

add Arnaldo Carvalho de Melo 


On 11/28/2017 02:13 PM, Li Zhijian wrote:

since 6aa7de0, we failed to build perf with C++(clang)
to fix the following compile errors
--
lizhijian@haswell-OptiPlex-9020:~/lkp/linux/tools/perf$ make 
LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
...
   CC   util/probe-finder.o
In file included from /home/lizj/linux/tools/perf/util/util.h:13:0,
  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/asm/../../arch/x86/include/asm/atomic.h: In 
function ‘int atomic_read(const atomic_t*)’:
/home/lizj/linux/tools/include/linux/compiler.h:157:45: error: use of deleted function 
‘atomic_read(const atomic_t*)()’
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
  ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: note: ‘atomic_read(const 
atomic_t*)()’ is implicitly deleted because 
the default definition would be ill-formed:
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: error: uninitialized const 
member in ‘union atomic_read(const atomic_t*)::’
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
/home/lizj/linux/tools/include/linux/compiler.h:157:23: note: ‘const int 
atomic_read(const atomic_t*)__val’ should be initialized
   ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
   return READ_ONCE((v)->counter);
  ^
   LD   tests/perf-in.o
...
--

Signed-off-by: Li Zhijian 
---
  tools/include/linux/compiler.h | 5 +
  1 file changed, 5 insertions(+)

diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 07fd03c..e4c8a0d 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -86,6 +86,10 @@
  
  #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
  
+#ifdef __cplusplus

+#define READ_ONCE(x) ACCESS_ONCE(x)
+#define WRITE_ONCE(x, val) ACCESS_ONCE(x) = val
+#else
  #include 
  
  /*

@@ -160,6 +164,7 @@ static __always_inline void __write_once_size(volatile void 
*p, void *res, int s
  #define WRITE_ONCE(x, val) \
({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; 
__write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
  
+#endif /* __cplusplus */
  
  #ifndef __fallthrough

  # define __fallthrough

[PATCH] tools include: define READ_ONCE/WRITE_ONCE for C++

2017-11-27 Thread Li Zhijian 
since 6aa7de0, we failed to build perf with C++(clang)
to fix the following compile errors
--
lizhijian@haswell-OptiPlex-9020:~/lkp/linux/tools/perf$ make 
LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
...
  CC   util/probe-finder.o
In file included from /home/lizj/linux/tools/perf/util/util.h:13:0,
 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/asm/../../arch/x86/include/asm/atomic.h: In 
function ‘int atomic_read(const atomic_t*)’:
/home/lizj/linux/tools/include/linux/compiler.h:157:45: error: use of deleted 
function ‘atomic_read(const atomic_t*)()’
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
 ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: note: 
‘atomic_read(const atomic_t*)()’ is 
implicitly deleted because the default definition would be ill-formed:
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: error: uninitialized 
const member in ‘union atomic_read(const atomic_t*)::’
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:23: note: ‘const int 
atomic_read(const atomic_t*)__val’ should be initialized
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
  LD   tests/perf-in.o
...
--

Signed-off-by: Li Zhijian 
---
 tools/include/linux/compiler.h | 5 +
 1 file changed, 5 insertions(+)

diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 07fd03c..e4c8a0d 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -86,6 +86,10 @@
 
 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
 
+#ifdef __cplusplus
+#define READ_ONCE(x) ACCESS_ONCE(x)
+#define WRITE_ONCE(x, val) ACCESS_ONCE(x) = val
+#else
 #include 
 
 /*
@@ -160,6 +164,7 @@ static __always_inline void __write_once_size(volatile void 
*p, void *res, int s
 #define WRITE_ONCE(x, val) \
({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; 
__write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
 
+#endif /* __cplusplus */
 
 #ifndef __fallthrough
 # define __fallthrough
-- 
2.7.4

[PATCH] tools include: define READ_ONCE/WRITE_ONCE for C++

2017-11-27 Thread Li Zhijian 
since 6aa7de0, we failed to build perf with C++(clang)
to fix the following compile errors
--
lizhijian@haswell-OptiPlex-9020:~/lkp/linux/tools/perf$ make 
LLVM_CONFIG=/usr/bin/llvm-config-3.9 LIBCLANGLLVM=1
...
  CC   util/probe-finder.o
In file included from /home/lizj/linux/tools/perf/util/util.h:13:0,
 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/asm/../../arch/x86/include/asm/atomic.h: In 
function ‘int atomic_read(const atomic_t*)’:
/home/lizj/linux/tools/include/linux/compiler.h:157:45: error: use of deleted 
function ‘atomic_read(const atomic_t*)()’
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
 ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: note: 
‘atomic_read(const atomic_t*)()’ is 
implicitly deleted because the default definition would be ill-formed:
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:11: error: uninitialized 
const member in ‘union atomic_read(const atomic_t*)::’
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
/home/lizj/linux/tools/include/linux/compiler.h:157:23: note: ‘const int 
atomic_read(const atomic_t*)__val’ should be initialized
  ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), 
__u.__c, sizeof(x)); __u.__val; })
   ^
/home/lizj/linux/tools/include/asm/../../arch/x86/include/asm/atomic.h:28:9: 
note: in expansion of macro ‘READ_ONCE’
  return READ_ONCE((v)->counter);
 ^
  LD   tests/perf-in.o
...
--

Signed-off-by: Li Zhijian 
---
 tools/include/linux/compiler.h | 5 +
 1 file changed, 5 insertions(+)

diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 07fd03c..e4c8a0d 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -86,6 +86,10 @@
 
 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
 
+#ifdef __cplusplus
+#define READ_ONCE(x) ACCESS_ONCE(x)
+#define WRITE_ONCE(x, val) ACCESS_ONCE(x) = val
+#else
 #include 
 
 /*
@@ -160,6 +164,7 @@ static __always_inline void __write_once_size(volatile void 
*p, void *res, int s
 #define WRITE_ONCE(x, val) \
({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; 
__write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
 
+#endif /* __cplusplus */
 
 #ifndef __fallthrough
 # define __fallthrough
-- 
2.7.4