sched/core: Add __sched tag for io_schedule()

Non-inline io_schedule() was introduced in:

  commit 10ab564 ("sched/core: Separate out io_schedule_prepare() and io_schedule_finish()")

Keep in line with io_schedule_timeout(), otherwise "/proc/<pid>/wchan" will
report io_schedule() rather than its callers when waiting for IO.

Reported-by: Jilong Kou <[email protected]>
Signed-off-by: Gao Xiang <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Miao Xie <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Fixes: 10ab564 ("sched/core: Separate out io_schedule_prepare() and io_schedule_finish()")
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

Author: Gao Xiang

kernel/sched/core.c

@@ -5122,7 +5122,7 @@ long __sched io_schedule_timeout(long timeout)
 }
 EXPORT_SYMBOL(io_schedule_timeout);
 
-void io_schedule(void)
+void __sched io_schedule(void)
 {
 	int token;