y2038: sched: Change sched_rr_get_interval to use __kernel_timespec

This is a preparation patch for converting sys_sched_rr_get_interval to
work with 64-bit time_t on 32-bit architectures. The 'interval' argument
is changed to struct __kernel_timespec, which will be redefined using
64-bit time_t in the future. The compat version of the system call in
turn is enabled for compilation with CONFIG_COMPAT_32BIT_TIME so
the individual 32-bit architectures can share the handling of the
traditional argument with 64-bit architectures providing it for their
compat mode.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

include/linux/syscalls.h

@@ -614,7 +614,7 @@ asmlinkage long sys_sched_yield(void);
 asmlinkage long sys_sched_get_priority_max(int policy);
 asmlinkage long sys_sched_get_priority_min(int policy);
 asmlinkage long sys_sched_rr_get_interval(pid_t pid,
-					struct timespec __user *interval);
+				struct __kernel_timespec __user *interval);
 
 /* kernel/signal.c */
 asmlinkage long sys_restart_syscall(void);

kernel/sched/core.c

@@ -5243,7 +5243,7 @@ static int sched_rr_get_interval(pid_t pid, struct timespec64 *t)
  * an error code.
  */
 SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
-		struct timespec __user *, interval)
+		struct __kernel_timespec __user *, interval)
 {
 	struct timespec64 t;
 	int retval = sched_rr_get_interval(pid, &t);
@@ -5254,7 +5254,7 @@ SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
 	return retval;
 }
 
-#ifdef CONFIG_COMPAT
+#ifdef CONFIG_COMPAT_32BIT_TIME
 COMPAT_SYSCALL_DEFINE2(sched_rr_get_interval,
 		       compat_pid_t, pid,
 		       struct old_timespec32 __user *, interval)