Messages in this thread | | | Subject | Re: [PATCH 3/3] x86: OLPC: speed up device tree creation during boot (v2) | From | Michael Ellerman <> | Date | Thu, 18 Nov 2010 22:02:15 +1100 |
| |
On Thu, 2010-11-18 at 09:34 +0100, Ingo Molnar wrote: > * H. Peter Anvin <hpa@zytor.com> wrote: > > > On 11/14/2010 11:02 PM, Ingo Molnar wrote: > > > > > > * H. Peter Anvin <hpa@zytor.com> wrote: > > > > > >> What? What is wrong with static variables in functions? It really doesn't seem > > >> to be a good idea to make them file-scope if they don't need to be. > > > > > > They are very easy to overlook and mix up with regular stack variables and i've seen > > > (and introduced myself) a number of bugs due to them. > > > > > > They also often are used in buggy ways (with SMP not taken into consideration), so > > > overlooking them during review compounds their negative effects. Putting them in > > > front of the function isnt a big deal in exchange. > > > > > > There are people who never overlook them (like yourself), but my brain is wired up > > > differently. > > > > > > > However, I have to vehemently object to putting them in a wider scope > > than is otherwise necessary. I agree that static variables should be > > used sparsely if at all (there really are vary few uses of them that are > > valid), but putting them in a larger scope screams "I'm used in more > > than one function", and that is *not* a good thing. > > That's why we sometimes use the (imperfect) compromise to put them in front of that > function, not at the top of the file. > > Look at the general balance of hardship: very little harm is done (it's not a big > deal if a variable is only used in a single function) but having it with local > variables can be _really_ harmful - for example i overlooked them when i reviewed > this patch. I dont like important details obscured - i like them to be apparent. > Again, this is something that some people can parse immediately on the visual level > - me and many others cannot.
What about:
int foo(void) { static int bar;
struct thing_struct *thing; int other_var; char *p;
... }
I think the visual wrongness of that formatting would be enough for me to stop and look twice. Though I guess it doesn't work if you have few, or no other variables other than the statics to declare.
cheers
[unhandled content-type:application/pgp-signature] | |