On Mon, 2 Jul 2007, Ulrich Drepper wrote: > On 7/1/07, Davide Libenzi <[EMAIL PROTECTED]> wrote: > > With the current API design you'd able to easily confine the "pre" code > > inside the "set" function, and the "post" code inside the "unset" > > function. It looks pretty clean to me, and allows to limit the knowledge > > of sys_indirect, the more as possible inside kernel/indirect.c. > > But this will not be applicable. We already discussed that each > syscall likely needs its own set of flags etc. There really isn't > much overlap if any which cannot be handled at least as well using a > flat structure. You're adding major complications for something which > IMO will never be usable. With the flat structure to whole overhead > of sys_indirect is limited to a test for valid syscalls, copying the > struct, making the call to the syscall function, and resetting the > value in current. Very simple and fast.
Never be usable? I made you a concrete example that is like 8 months old. And *that* could not have been cleanly handled with the flat structure idea. The extra flags parameter is one example where we'd need an extra flags field in the task_struct in any case. So you need in any case code that does extra checks and merges normal parameters/flags with the shared context ones. This independently of the method used. But there are examples (and the signal stuff is one of them), where you do need the set_context+syscall+unset_context abstraction, for all cases where the kernel already has its own internal data strctures. In those cases you'd have to spread sys_internal context knowledge all around the kernel, whereas the current solution allows you to confine the code inside kernel/indirect.c (through the set/unset abstraction). And this w/out even try to hit the weak spot of about how this structure will look after a few additions. - Davide - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
