On Fri, Sep 04, 2020 at 10:16:10AM +0800, Boqun Feng wrote:
> Hi Paul,
>
> On Mon, Aug 31, 2020 at 11:14:15AM -0700, [email protected] wrote:
> > From: "Paul E. McKenney" <[email protected]>
> >
> > This commit adds a destination CPU to __call_single_data, and is inspired
> > by an earlier commit by Peter Zijlstra. This version adds #ifdef to
> > permit use by 32-bit systems and supplying the destination CPU for all
> > smp_call_function*() requests, not just smp_call_function_single().
> >
> > If need be, 32-bit systems could be accommodated by shrinking the flags
> > field to 16 bits (the atomic_t variant is currently unused) and by
> > providing only eight bits for CPU on such systems.
> >
> > It is not clear that the addition of the fields to __call_single_node
> > are really needed.
> >
> > Link:
> > https://lore.kernel.org/lkml/[email protected]/
> > Cc: Peter Zijlstra <[email protected]>
> > Cc: Ingo Molnar <[email protected]>
> > Cc: Thomas Gleixner <[email protected]>
> > Cc: Sebastian Andrzej Siewior <[email protected]>
> > Cc: Frederic Weisbecker <[email protected]>
> > Signed-off-by: Paul E. McKenney <[email protected]>
> > ---
> > include/linux/smp.h | 3 +++
> > include/linux/smp_types.h | 3 +++
> > kernel/smp.c | 2 ++
> > 3 files changed, 8 insertions(+)
> >
> > diff --git a/include/linux/smp.h b/include/linux/smp.h
> > index 80d557e..9f13966 100644
> > --- a/include/linux/smp.h
> > +++ b/include/linux/smp.h
> > @@ -26,6 +26,9 @@ struct __call_single_data {
> > struct {
> > struct llist_node llist;
> > unsigned int flags;
> > +#ifdef CONFIG_64BIT
> > + u16 src, dst;
> > +#endif
> > };
> > };
> > smp_call_func_t func;
> > diff --git a/include/linux/smp_types.h b/include/linux/smp_types.h
> > index 364b3ae..2e8461a 100644
> > --- a/include/linux/smp_types.h
> > +++ b/include/linux/smp_types.h
> > @@ -61,6 +61,9 @@ struct __call_single_node {
> > unsigned int u_flags;
> > atomic_t a_flags;
> > };
> > +#ifdef CONFIG_64BIT
> > + u16 src, dst;
> > +#endif
> > };
> >
> > #endif /* __LINUX_SMP_TYPES_H */
> > diff --git a/kernel/smp.c b/kernel/smp.c
> > index d0ae8eb..a47382d 100644
> > --- a/kernel/smp.c
> > +++ b/kernel/smp.c
> > @@ -375,6 +375,7 @@ int smp_call_function_single(int cpu, smp_call_func_t
> > func, void *info,
> >
> > csd->func = func;
> > csd->info = info;
> > + csd->dst = cpu;
>
> Would this and the next modification cause compile errors with
> CONFIG_64BIT = n? I saw you add #ifdef guard in the next patch, so maybe
> move those two into next patch (of course, if they trigger compile
> errors)
Good point, will fix, thank you!
Thanx, Paul
> Regards,
> Boqun
>
> >
> > err = generic_exec_single(cpu, csd);
> >
> > @@ -540,6 +541,7 @@ static void smp_call_function_many_cond(const struct
> > cpumask *mask,
> > csd->flags |= CSD_TYPE_SYNC;
> > csd->func = func;
> > csd->info = info;
> > + csd->dst = cpu;
> > if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
> > __cpumask_set_cpu(cpu, cfd->cpumask_ipi);
> > }
> > --
> > 2.9.5
> >
