[PATCH v3 2/7] kernel.h: Split out container_of() and typeof_member() macros

Andy Shevchenko
2021-10-07T15:04:55Z

kernel.h is being used as a dump for all kinds of stuff for a long time.
Here is the attempt cleaning it up by splitting out container_of() and
typeof_member() macros.

For time being include new header back to kernel.h to avoid twisted
indirected includes for existing users.

Note, there are _a lot_ of headers and modules that include kernel.h solely
for one of these macros and this allows to unburden compiler for the twisted
inclusion paths and to make new code cleaner in the future.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
include/linux/container_of.h | 37 ++++++++++++++++++++++++++++++++++++
include/linux/kernel.h | 31 +-----------------------------
include/linux/kobject.h | 1 +
3 files changed, 39 insertions(+), 30 deletions(-)
create mode 100644 include/linux/container_of.h

diff --git a/include/linux/container_of.h b/include/linux/container_of.h
new file mode 100644
index 000000000000..f6ee1be0e784
--- /dev/null
+++ b/include/linux/container_of.h
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_CONTAINER_OF_H
+#define _LINUX_CONTAINER_OF_H
+
+#define typeof_member(T, m) typeof(((T*)0)->m)
+
+/**
+ * container_of - cast a member of a structure out to the containing structure
+ * @ptr: the pointer to the member.
+ * @type: the type of the container struct this is embedded in.
+ * @member: the name of the member within the struct.
+ *
+ */
+#define container_of(ptr, type, member) ({ \
+ void *__mptr = (void *)(ptr); \
+ BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \
+ !__same_type(*(ptr), void), \
+ "pointer type mismatch in container_of()"); \
+ ((type *)(__mptr - offsetof(type, member))); })
+
+/**
+ * container_of_safe - cast a member of a structure out to the containing structure
+ * @ptr: the pointer to the member.
+ * @type: the type of the container struct this is embedded in.
+ * @member: the name of the member within the struct.
+ *
+ * If IS_ERR_OR_NULL(ptr), ptr is returned unchanged.
+ */
+#define container_of_safe(ptr, type, member) ({ \
+ void *__mptr = (void *)(ptr); \
+ BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \
+ !__same_type(*(ptr), void), \
+ "pointer type mismatch in container_of()"); \
+ IS_ERR_OR_NULL(__mptr) ? ERR_CAST(__mptr) : \
+ ((type *)(__mptr - offsetof(type, member))); })
+
+#endif /* _LINUX_CONTAINER_OF_H */
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index d416fe3165cb..ad9fdcce9dcf 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -9,6 +9,7 @@
#include <linux/stddef.h>
#include <linux/types.h>
#include <linux/compiler.h>
+#include <linux/container_of.h>
#include <linux/bitops.h>
#include <linux/kstrtox.h>
#include <linux/log2.h>
@@ -482,36 +483,6 @@ static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
#define __CONCAT(a, b) a ## b
#define CONCATENATE(a, b) __CONCAT(a, b)

-/**
- * container_of - cast a member of a structure out to the containing structure
- * @ptr: the pointer to the member.
- * @type: the type of the container struct this is embedded in.
- * @member: the name of the member within the struct.
- *
- */
-#define container_of(ptr, type, member) ({ \
- void *__mptr = (void *)(ptr); \
- BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \
- !__same_type(*(ptr), void), \
- "pointer type mismatch in container_of()"); \
- ((type *)(__mptr - offsetof(type, member))); })
-
-/**
- * container_of_safe - cast a member of a structure out to the containing structure
- * @ptr: the pointer to the member.
- * @type: the type of the container struct this is embedded in.
- * @member: the name of the member within the struct.
- *
- * If IS_ERR_OR_NULL(ptr), ptr is returned unchanged.
- */
-#define container_of_safe(ptr, type, member) ({ \
- void *__mptr = (void *)(ptr); \
- BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \
- !__same_type(*(ptr), void), \
- "pointer type mismatch in container_of()"); \
- IS_ERR_OR_NULL(__mptr) ? ERR_CAST(__mptr) : \
- ((type *)(__mptr - offsetof(type, member))); })
-
/* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
# define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index efd56f990a46..bf8371e58b17 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -15,6 +15,7 @@
#ifndef _KOBJECT_H_
#define _KOBJECT_H_

+#include <linux/container_of.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/sysfs.h>
--
2.33.0