Re: [patch] threading fix, tid-2.5.47-A3

From: Ingo Molnar (mingo@elte.hu)
Date: Sun Nov 17 2002 - 16:17:49 EST


On 17 Nov 2002, Luca Barbieri wrote:

> The new definition of the clone flags is binary incompatible with older
> 2.5 kernels.

we broke binary compatibility several times, for the benefit of having a
cleaner interface. Ulrich has no problems with this approach and NPTL is
the only user of these interfaces currently. But i think you are one of
the few peoples who are running an NPTL system (ie. with the new
NPTL-glibc actually installed as the default system glibc) - is binary
compatibility important to you for this specific case?

> > -#if CONFIG_SMP || CONFIG_PREEMPT
> > +asmlinkage void FASTCALL(schedule_tail(task_t *prev));
> > asmlinkage void schedule_tail(task_t *prev)
> > {
> > finish_arch_switch(this_rq(), prev);
> Maybe finish_arch_switch should only be called if CONFIG_SMP ||
> CONFIG_PREEMPT, like what happened without this patch?

finish_arch_switch() is a no-op on UP. (well, almost, i'll fix that.)

> > + if (clone_flags & CLONE_PARENT_SETTID)
> > + put_user(p->pid, parent_tidptr);
> How about failing if put_user fails?

we could do that - although we cannot fail the CHILD_SETTID variant, and i
wanted to keep it symmetric.

        Ingo

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