path: root/Documentation/CodingStyle
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authorRobert P. J. Day <rpjday@mindspring.com>2006-12-22 01:09:11 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-22 08:55:49 -0800
commit58637ec90b7ceed5909e726ac90118852f79d2b1 (patch)
treef5478b2f088d31b609ed07bb10fb641bad7cd10e /Documentation/CodingStyle
parent163ca88b9c5858909ee3f8801ae0096b5f94e835 (diff)
[PATCH] Add a new section to CodingStyle, promoting include/linux/kernel.h
Add a new section to the CodingStyle file, encouraging people not to re-invent available kernel macros such as ARRAY_SIZE(), FIELD_SIZEOF(), min() and max(), among others. Signed-off-by: Robert P. J. Day <rpjday@mindspring.com> Acked-by: Randy Dunlap <randy.dunlap@oracle.com> Acked-by: Jan Engelhardt <jengelh@gmx.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@@ -682,6 +682,24 @@ result. Typical examples would be functions that return pointers; they use
NULL or the ERR_PTR mechanism to report failure.
+ Chapter 17: Don't re-invent the kernel macros
+The header file include/linux/kernel.h contains a number of macros that
+you should use, rather than explicitly coding some variant of them yourself.
+For example, if you need to calculate the length of an array, take advantage
+of the macro
+ #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+Similarly, if you need to calculate the size of some structure member, use
+ #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
+There are also min() and max() macros that do strict type checking if you
+need them. Feel free to peruse that header file to see what else is already
+defined that you shouldn't reproduce in your code.
Appendix I: References