On Tue, Aug 25, 2015 at 08:45:18PM +0200, Oleg Nesterov wrote:
> The code like
>
> const int n = const-expr;
> whatever_t array[n];
>
> in inline function can confuse gcc, see
>
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67055#c13
>
> This leads to
>
> In file included from include/linux/rcupdate.h:429:0,
> from include/linux/rcusync.h:5,
> from kernel/rcu/sync.c:1:
> include/linux/rcutiny.h: In function 'rcu_barrier_sched':
> include/linux/rcutiny.h:55:20: internal compiler error: Segmentation
> fault
> static inline void rcu_barrier_sched(void)
>
> build failure after ec90a194a "rcu: Create a synchronize_rcu_mult()"
> and 114b7fd4b "rcu: Create rcu_sync infrastructure" meet each other.
>
> Reported-and-tested-by: Mark Salter <msal...@redhat.com>
> Reported-by: Guenter Roeck <li...@roeck-us.net>
> Signed-off-by: Oleg Nesterov <o...@redhat.com>
Ouch!!! Queued for testing, in the absence of problems, will push into
the upcoming merge window.
Thank you all for the testing and the fix!
Thanx, Paul
> ---
> include/linux/rcupdate.h | 11 +++++------
> 1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
> index ff47651..c353c2b 100644
> --- 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__)
> --
> 2.4.3
>
>
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