Commit 66e8c57d authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Paul E. McKenney

rcu: Change _wait_rcu_gp() to work around GCC bug 67055

Code like this in inline functions confuses some recent versions of gcc:

	const int n = const-expr;
	whatever_t array[n];

For more details, see:

	https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67055#c13

This compiler bug results in the following failure after 114b7fd4b (rcu:
Create rcu_sync infrastructure):

	In file included from include/linux/rcupdate.h:429:0,
			  from include/linux/rcu_sync.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)

This commit therefore eliminates the constant local variable in favor of
direct use of the expression.
Reported-and-tested-by: default avatarMark Salter <msalter@redhat.com>
Reported-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 1f93e4a9
...@@ -230,12 +230,11 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array, ...@@ -230,12 +230,11 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
struct rcu_synchronize *rs_array); struct rcu_synchronize *rs_array);
#define _wait_rcu_gp(checktiny, ...) \ #define _wait_rcu_gp(checktiny, ...) \
do { \ do { \
call_rcu_func_t __crcu_array[] = { __VA_ARGS__ }; \ call_rcu_func_t __crcu_array[] = { __VA_ARGS__ }; \
const int __n = ARRAY_SIZE(__crcu_array); \ struct rcu_synchronize __rs_array[ARRAY_SIZE(__crcu_array)]; \
struct rcu_synchronize __rs_array[__n]; \ __wait_rcu_gp(checktiny, ARRAY_SIZE(__crcu_array), \
\ __crcu_array, __rs_array); \
__wait_rcu_gp(checktiny, __n, __crcu_array, __rs_array); \
} while (0) } while (0)
#define wait_rcu_gp(...) _wait_rcu_gp(false, __VA_ARGS__) #define wait_rcu_gp(...) _wait_rcu_gp(false, __VA_ARGS__)
......
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