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Commit 6de16eba authored by Jonathan Corbet's avatar Jonathan Corbet
Browse files

Docs: Remove "tips and tricks" from SubmittingPatches 



This section was just a weird collection of stuff that is better found
elsewhere.  The "coding style" section somewhat duplicated the previous
coding style section; the useful information there has been collected into
a single place.

Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent 97bf6af1

Documentation/SubmittingPatches

+21 −96
Original line number Diff line number Diff line
@@ -193,17 +193,33 @@ then only post say 15 or so at a time and wait for review and integration. 






4) Style check your changes.

4) Style-check your changes.

----------------------------



Check your patch for basic style violations, details of which can be

found in Documentation/CodingStyle.  Failure to do so simply wastes

the reviewers time and will get your patch rejected, probably

without even being read.



At a minimum you should check your patches with the patch style

checker prior to submission (scripts/checkpatch.pl).  You should

be able to justify all violations that remain in your patch.

One significant exception is when moving code from one file to

another -- in this case you should not modify the moved code at all in

the same patch which moves it.  This clearly delineates the act of

moving the code and your changes.  This greatly aids review of the

actual differences and allows tools to better track the history of

the code itself.



Check your patches with the patch style checker prior to submission

(scripts/checkpatch.pl).  Note, though, that the style checker should be

viewed as a guide, not as a replacement for human judgment.  If your code

looks better with a violation then its probably best left alone.



The checker reports at three levels:

 - ERROR: things that are very likely to be wrong

 - WARNING: things requiring careful review

 - CHECK: things requiring thought



You should be able to justify all violations that remain in your

patch.





5) Select e-mail destination.
@@ -684,100 +700,9 @@ new/deleted or renamed files. 
With rename detection, the statistics are rather different [...]

because git will notice that a fair number of the changes are renames.



-----------------------------------

SECTION 2 - HINTS, TIPS, AND TRICKS

-----------------------------------



This section lists many of the common "rules" associated with code

submitted to the kernel.  There are always exceptions... but you must

have a really good reason for doing so.  You could probably call this

section Linus Computer Science 101.







1) Read Documentation/CodingStyle



Nuff said.  If your code deviates too much from this, it is likely

to be rejected without further review, and without comment.



One significant exception is when moving code from one file to

another -- in this case you should not modify the moved code at all in

the same patch which moves it.  This clearly delineates the act of

moving the code and your changes.  This greatly aids review of the

actual differences and allows tools to better track the history of

the code itself.



Check your patches with the patch style checker prior to submission

(scripts/checkpatch.pl).  The style checker should be viewed as

a guide not as the final word.  If your code looks better with

a violation then its probably best left alone.



The checker reports at three levels:

 - ERROR: things that are very likely to be wrong

 - WARNING: things requiring careful review

 - CHECK: things requiring thought



You should be able to justify all violations that remain in your

patch.







2) #ifdefs are ugly



Code cluttered with ifdefs is difficult to read and maintain.  Don't do

it.  Instead, put your ifdefs in a header, and conditionally define

'static inline' functions, or macros, which are used in the code.

Let the compiler optimize away the "no-op" case.



Simple example, of poor code:



	dev = alloc_etherdev (sizeof(struct funky_private));

	if (!dev)

		return -ENODEV;

	#ifdef CONFIG_NET_FUNKINESS

	init_funky_net(dev);

	#endif



Cleaned-up example:



(in header)

	#ifndef CONFIG_NET_FUNKINESS

	static inline void init_funky_net (struct net_device *d) {}

	#endif



(in the code itself)

	dev = alloc_etherdev (sizeof(struct funky_private));

	if (!dev)

		return -ENODEV;

	init_funky_net(dev);







3) 'static inline' is better than a macro



Static inline functions are greatly preferred over macros.

They provide type safety, have no length limitations, no formatting

limitations, and under gcc they are as cheap as macros.



Macros should only be used for cases where a static inline is clearly

suboptimal [there are a few, isolated cases of this in fast paths],

or where it is impossible to use a static inline function [such as

string-izing].



'static inline' is preferred over 'static __inline__', 'extern inline',

and 'extern __inline__'.







4) Don't over-design.



Don't try to anticipate nebulous future cases which may or may not

be useful:  "Make it as simple as you can, and no simpler."







----------------------

SECTION 3 - REFERENCES

SECTION 2 - REFERENCES

----------------------



Andrew Morton, "The perfect patch" (tpp).