[PATCH v4 1/5] tools: add container_of() macro to xen-tools/common-macros.h

[Juergen Gross <jgross@xxxxxxxx>]

Instead of having 4 identical copies of the definition of a
container_of() macro in different tools header files, add that macro
to xen-tools/common-macros.h and use that instead.

Delete the other copies of that macro.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
There is a similar macro CONTAINER_OF() defined in
tools/include/xentoolcore_internal.h, which allows to not only use a
type for the 2nd parameter, but a variable, too.
I'd like to get rid of that macro as well, but there are lots of use
cases especially in libxl. Any thoughts regarding that macro?
I could either:
- don't touch it at all
- enhance container_of() like CONTAINER_OF() and replace all use cases
  of CONTAINER_OF() with container_of()
- replace the few CONTAINER_OF() users outside libxl with container_of()
  and define CONTAINER_OF() in e.g. libxl_internal.h
- replace all CONTAINER_OF() use cases with container_of(), including
  the change from (.., var, ..) to (.., type, ...).

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 tools/include/xen-tools/common-macros.h | 4 ++++
 tools/tests/vpci/emul.h                 | 6 +-----
 tools/tests/x86_emulator/x86-emulate.h  | 5 -----
 tools/xenstore/list.h                   | 6 ++----
 4 files changed, 7 insertions(+), 14 deletions(-)

diff --git a/tools/include/xen-tools/common-macros.h 
b/tools/include/xen-tools/common-macros.h
index a372b9ecf2..b046ab48bf 100644
--- a/tools/include/xen-tools/common-macros.h
+++ b/tools/include/xen-tools/common-macros.h
@@ -76,4 +76,8 @@
 #define __must_check __attribute__((__warn_unused_result__))
 #endif
 
+#define container_of(ptr, type, member) ({                \
+    typeof( ((type *)0)->member ) *__mptr = (ptr);        \
+    (type *)( (char *)__mptr - offsetof(type,member) );})
+
 #endif /* __XEN_TOOLS_COMMON_MACROS__ */
diff --git a/tools/tests/vpci/emul.h b/tools/tests/vpci/emul.h
index f03e3a56d1..7169a2ea02 100644
--- a/tools/tests/vpci/emul.h
+++ b/tools/tests/vpci/emul.h
@@ -27,11 +27,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-#define container_of(ptr, type, member) ({                      \
-        typeof(((type *)0)->member) *mptr = (ptr);              \
-                                                                \
-        (type *)((char *)mptr - offsetof(type, member));        \
-})
+#include <xen-tools/common-macros.h>
 
 #define smp_wmb()
 #define prefetch(x) __builtin_prefetch(x)
diff --git a/tools/tests/x86_emulator/x86-emulate.h 
b/tools/tests/x86_emulator/x86-emulate.h
index 46d4e43cea..1af986f78d 100644
--- a/tools/tests/x86_emulator/x86-emulate.h
+++ b/tools/tests/x86_emulator/x86-emulate.h
@@ -56,11 +56,6 @@
 
 #define cf_check /* No Control Flow Integriy checking */
 
-#define container_of(ptr, type, member) ({             \
-    typeof(((type *)0)->member) *mptr__ = (ptr);       \
-    (type *)((char *)mptr__ - offsetof(type, member)); \
-})
-
 #define AC_(n,t) (n##t)
 #define _AC(n,t) AC_(n,t)
 
diff --git a/tools/xenstore/list.h b/tools/xenstore/list.h
index b17d13e0ec..a464a38b61 100644
--- a/tools/xenstore/list.h
+++ b/tools/xenstore/list.h
@@ -3,6 +3,8 @@
 /* Taken from Linux kernel code, but de-kernelized for userspace. */
 #include <stddef.h>
 
+#include <xen-tools/common-macros.h>
+
 #undef LIST_HEAD_INIT
 #undef LIST_HEAD
 #undef INIT_LIST_HEAD
@@ -15,10 +17,6 @@
 #define LIST_POISON1  ((void *) 0x00100100)
 #define LIST_POISON2  ((void *) 0x00200200)
 
-#define container_of(ptr, type, member) ({                     \
-        typeof( ((type *)0)->member ) *__mptr = (ptr); \
-        (type *)( (char *)__mptr - offsetof(type,member) );})
-
 /*
  * Simple doubly linked list implementation.
  *
-- 
2.35.3