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 <[email protected]>
---
NOTE: at the moment, there is not a single invocation of the
FIELD_SIZEOF() macro anywhere in the entire source tree, so if someone
had a hankering to rename it to something more catchy, now would be a
good time and i can always resubmit the patch i sent in yesterday.
diff --git a/Documentation/CodingStyle b/Documentation/CodingStyle
index 0ad6dcb..a736333 100644
--- a/Documentation/CodingStyle
+++ b/Documentation/CodingStyle
@@ -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
On Mon, 18 Dec 2006 12:43:35 -0500 (EST) Robert P. J. Day wrote:
>
> 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 <[email protected]>
Acked-by: Randy Dunlap <[email protected]>
> ---
>
> NOTE: at the moment, there is not a single invocation of the
> FIELD_SIZEOF() macro anywhere in the entire source tree, so if someone
> had a hankering to rename it to something more catchy, now would be a
> good time and i can always resubmit the patch i sent in yesterday.
>
>
>
> diff --git a/Documentation/CodingStyle b/Documentation/CodingStyle
> index 0ad6dcb..a736333 100644
> --- a/Documentation/CodingStyle
> +++ b/Documentation/CodingStyle
> @@ -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
---
~Randy
> 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 <[email protected]>
Acked-by: Jan Engelhardt <[email protected]>
-`J'
--
On Mon, Dec 18, 2006 at 12:43:35PM -0500, Robert P. J. Day wrote:
> 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.
Good stuff. Could you also mention the printk() KERN_ALERT etc. levels?
I've seen quite some people using "<1>" on the kernelnewbies list.
Erik
--
+-- Erik Mouw -- http://www.harddisk-recovery.com -- +31 70 370 12 90 --
| Lab address: Delftechpark 26, 2628 XH, Delft, The Netherlands
On Mon, 18 Dec 2006, Erik Mouw wrote:
> On Mon, Dec 18, 2006 at 12:43:35PM -0500, Robert P. J. Day wrote:
> > 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.
>
> Good stuff. Could you also mention the printk() KERN_ALERT etc.
> levels? I've seen quite some people using "<1>" on the kernelnewbies
> list.
they may be using it on that list, but there's very little of that in
the kernel source itself. this is the only example i found:
$ grep -r '<[0-7]>' * | grep printk
arch/ppc/syslib/m8260_pci_erratum9.c: printk("<4>Using IDMA%d for MPC8260 device erratum PCI 9 workaround\n",
maybe i'll submit a patch to clean that one up.
rday