On Tue, 2005-12-13 at 08:54 +0100, Ingo Molnar wrote: > * Andrew Morton <[EMAIL PROTECTED]> wrote: > > > I'd have thought that the way to do this is to simply reimplement > > down(), up(), down_trylock(), etc using the new xchg-based code and to > > then hunt down those few parts of the kernel which actually use the > > old semaphore's counting feature and convert them to use down_sem(), > > up_sem(), etc. And rename all the old semaphore code: > > s/down/down_sem/etc. > > even better than that, why not use the solution that we've implemented > for the -rt patchset, more than a year ago? > > the solution i took was this: > > - i did not touch the 'struct semaphore' namespace, but introduced a > 'struct compat_semaphore'.
which I think is wrong. THis naming sucks. Sure doing a full sed on the tree is not pretty but it's also not THAT painful. And the pain of wrong names is something the kernel needs to carry around for years. > > - i introduced a 'type-sensitive' macro wrapper that switches down() > (and the other APIs) to either to the assembly variant (if the > variable's type is struct compat_semaphore), or switches it to the new > generic mutex (if the type is struct semaphore), at build-time. There > is no runtime overhead due to this build-time-switching. while this is a smart trick, I rather prefer seperate functions, just so that people are "aware" which they use. Since 99% of the users is a mutex anyway, the new names are only used in a few special cases.
