Re: h8300 build failures in linux-next (in rcu code, gcc 5.x related, not limited to h8300)

From: Mark Salter
Date: Tue Aug 25 2015 - 14:16:32 EST


On Tue, 2015-08-25 at 20:02 +0200, Oleg Nesterov wrote:
> On 08/25, Oleg Nesterov wrote:
> >
> > On 08/26, Yoshinori Sato wrote:
> > >
> > > Yes.
> > > gcc bug #67055.
> > > Already fixed in trunk.
> >
> > Yes, thanks a lot.
> >
> > Paul, it seems that gcc actually dislikes your ec90a194a "rcu:
> > Create a synchronize_rcu_mult()" commit ;) rcu/sync.c was just
> > lucky enough to trigger the problem.
> >
> > I'll try to make the fix today...
>
> Mark, Guenter, any chance you can check if the patch below helps?
> It does on x86.

Works for c6x.

>
> Oleg.
>
> --- a/include/linux/rcupdate.h
> +++ b/include/linux/rcupdate.h
> @@ -230,12 +230,11 @@ void __wait_rcu_gp(bool checktiny, int n,
> call_rcu_func_t *crcu_array,
> struct rcu_synchronize *rs_array);
>
> #define _wait_rcu_gp(checktiny, ...) \
> -do { \
> - call_rcu_func_t __crcu_array[] = { __VA_ARGS__ }; \
> - const int __n = ARRAY_SIZE(__crcu_array); \
> - struct rcu_synchronize __rs_array[__n]; \
> - \
> - __wait_rcu_gp(checktiny, __n, __crcu_array, __rs_array); \
> +do {
> \
> + call_rcu_func_t __crcu_array[] = { __VA_ARGS__ };
> \
> + struct rcu_synchronize __rs_array[ARRAY_SIZE(__crcu_array)];
> \
> + __wait_rcu_gp(checktiny, ARRAY_SIZE(__crcu_array),
> \
> + __crcu_array, __rs_array);
> \
> } while (0)
>
> #define wait_rcu_gp(...) _wait_rcu_gp(false, __VA_ARGS__)
>

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