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Re: [GIT PATCH] HID and USB HID update for 2.6.21-rc2
On Wed, 28 Feb 2007, Jiri Kosina wrote: > On Wed, 28 Feb 2007, Linus Torvalds wrote: > > > There is no excuse for putting a large array in a header file and > > including it millions of times. Or even just twice. The point of a > > header file is to *declare* things, not to have big data structures in. > > The point was that noone else than hid/hid-core.c would ever be going to > include this header with blacklist. So: - clearly other people *do* include it. - if no-one else incldues it WHY HAVE IT SEPARATE! - if you want to have it separate for other reasons, YOU MAKE IT A .c FILE, SINCE IT'S CLEARLY NOT A HEADERFILE! In other words, there is *zero* excuse for that braindamage. > But OK, I will leave it in there. No. You need to realize just WHY it was wrong. Not just an "But OK". Because if you don't see why I'm complaining, I can't pull from you. You can send me patches, but for me to pull a git patch from you, I need to know that you know what you're doing, and I need to be able to trust things *without* then having to go and check every individual change by hand. If I have to check changes like this by hand, I want you to send patches to the mailing list, so that other people can help me filter it out. It really is that simple, and that fundamental. It's about code flow, and it's about the fact that there's no way I can look at every change and vet it for being sane. I simply *cannot* do git-to-git merges with people I can't trust to have good enough judgement that I don't need to do the micromanagement and check everything myself. I can't afford to. I don't have the bandwidth, but I also simply don't have the interest in micro-managing. So people I do git merges with need to show that they have good taste and skills, otherwise it needs to be done as open patches where *other* people with good taste and skills can help me. Linus (Log in to post comments)
Some idle comments about Linus' e-mail response and Linux Posted Mar 1, 2007 5:20 UTC (Thu) by pr1268 (subscriber, #24648) [Link] Having read Linus' reply, I kind of get why Linux has been so successful: It's the quality assurance model of hundreds of skilled developers with good taste all looking out for each other. A network of trust has been built amongst some of the more experienced kernel hackers (People such as Andrew, Greg, Alan, Theodore, Adrian, Al, and others come to mind) who are given a bigger share of responsibility for ensuring the quality of the kernel code remains high. Plus, it seems anytime Linus' comments get posted on LWN, it's often a rant or tirade about sloppy kernel programming (if not about some marketing or legal blunder that negatively impacts Linux [i.e. DRM, etc.]). This is not meant as criticism. In fact, I bookmark a lot of these posts because Linus generally has nothing but adroit, intelligent advice on programming, operating system theory, and computers in general. I gather that Linux also owes much of its success to the idea that many FLOSS community members respect Linus for his expert knowledge. I certainly do. Enough with the Linus-gushing. I know the difference between skilled and unskilled kernel programming, but can someone give me an example of bad taste in programming? ;-)
Some idle comments about Linus' e-mail response and Linux Posted Mar 1, 2007 10:40 UTC (Thu) by ekj (guest, #1524) [Link] Taste is always going to be, to some degree, subjective.I think the example in the post is a decent example of bad taste: If you only include a header-file once, it doesn't make any difference if you declare some array there, or in a c-file, the compiler-generated code will be identical anyway. However, it is *bad-taste* because that isn't what generally belongs in header-files, which makes the code harder to understand for non-insiders, and which increases the risk of errors. Also, it starts being stupid the moment someone else gets the idea of including that header-file, unaware that it contains stuff that header-files do not normally contain. I'd classify as "bad-taste" programming that is not plainly wrong (as in buggy or as in wasteful), but which nevertheless;
Some idle comments about Linus' e-mail response and Linux Posted Mar 1, 2007 11:27 UTC (Thu) by k8to (subscriber, #15413) [Link] There's lots of forms of bad taste. Doing something in a complex sophisticated way when a simplistic straightforward way will get the job done fine is a "favorite" of mine.
But I think in design and engineering, bad taste is not very subjective. I think there is a high degree of consensus among people skilled in those fields about what is in bad taste. Sure there's some subjectivity, but I think it's, in practice, quite small.
Some idle comments about Linus' e-mail response and Linux Posted Mar 1, 2007 11:33 UTC (Thu) by Randakar (guest, #27808) [Link]
Linus's definition of 'bad taste' is not just limited to aesthetics and structure it seems. Quite often he hammers on deeper things:
- interfaces - does the interface make sense for the problem at hand?
- architecture. A good example there would be the suspend-to-ram vs suspend-to-disk discussion, where suspend-to-ram was generally broken because the whole suspend process was ill-defined from a conceptual standpoint, rather than from an aestetic one.
Bad taste in programming Posted Mar 1, 2007 17:14 UTC (Thu) by pr1268 (subscriber, #24648) [Link] Thanks to the above posters for your responses.... But I was thinking more low-level bad taste in kernel programming. ;-) As in:
But I suppose bad taste can exist at all levels of programming. Disclaimer: I am easily entertained by browsing code at the IOCCC Web site, but I whole-heartedly agree that it's absolutely no fun having to maintain sloppy code whose author exhibited bad taste. As for coding style (indentation, proper use of curly braces, etc.), Robert Love's book has some style guidelines for kernel code in one of the appendices. Not that I'm trying to plug his book or anything (but it is a decent read).
Bad taste in programming Posted Mar 1, 2007 18:45 UTC (Thu) by vmole (guest, #111) [Link] Your first three examples are not bad taste, but simply errors (well, 'for(;;;)' does have its occasional use, but in general...).
OTOH, regarding, the un-readable condition clause: there was a recent thread in lkml about this. Yes, it might be technically correct, but its undereadable and unverifiable to the casual reader. Much better to break up into shorter, independent check. So sayeth Torvalds. Sorry, don't have an exact pointer to the thread.
Bad taste in programming Posted Mar 2, 2007 16:57 UTC (Fri) by kleptog (subscriber, #1183) [Link] Actually, I like for(;;) because I find it stands out and looks better than while(1).
Bad taste in programming Posted Mar 2, 2007 18:48 UTC (Fri) by wcooley (guest, #1233) [Link] Sure, but the code in question wasn't "for(;;)"--it was "for(;;);"--a subtle but huge difference.
Infinite loops as bad taste Posted Mar 3, 2007 1:20 UTC (Sat) by pr1268 (subscriber, #24648) [Link] Actually, I was taught that for(;;) is faster than while(1) since the former doesn't need to perform a logical evaluation, but the latter does. (Wouldn't this be a weird flame war debate?) I'm since convinced that this is old news, since my experiences hacking some C/C++ code with gcc -S and gcc -c show identical .s and .o files in either case (optimized or not). I recently coded a loop as for(;;i++) { /* ... */ } (don't ask). :^)
Infinite loops as bad taste Posted Mar 5, 2007 6:15 UTC (Mon) by landley (guest, #6789) [Link] > Actually, I was taught that for(;;) is faster than while(1)
And circa 1984, this was true.
Compilers change. Optimizers change. Hardware changes drastically. (2
x=5;
This is now generally faster than:
Why? Branch prediction with conditional assignments to avoid bubbles in
However, 90% of the time you don't have to _care_ because your compiler
And if you religiously write #1 it's possible that in 5 years new hardware
Remember Ken Thompson's "When it doubt, use brute force" because it's darn
That said, I use for(;;) because I think it's cleaner. (It lies to the
Bad taste in programming Posted Mar 2, 2007 22:16 UTC (Fri) by maney (subscriber, #12630) [Link] /* New kernel idle loop */for(;;); Aw, man, don't do that - Ballmer's already ranting about his missing IP as it is.
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