[RFC PATCH v1 1/9] timer: fix circular header dependency

[Christophe Leroy]

When switching powerpc to CONFIG_THREAD_INFO_IN_TASK, include/sched.h
has to be included in asm/smp.h for the following change, in order
to avoid uncomplete definition of task_struct:

-#define raw_smp_processor_id() (current_thread_info()->cpu)
+#define raw_smp_processor_id() (current->cpu)

But this generates the following compilation error, due to circular
header dependency.

  CC      kernel/time/alarmtimer.o
In file included from ./arch/powerpc/include/asm/smp.h:31,
                 from ./include/linux/smp.h:64,
                 from ./include/linux/percpu.h:7,
                 from ./include/linux/hrtimer.h:22,
                 from kernel/time/alarmtimer.c:19:
./include/linux/sched.h:558:19: error: field 'dl_timer' has incomplete type
  struct hrtimer   dl_timer;
                   ^~~~~~~~
./include/linux/sched.h:567:17: error: field 'inactive_timer' has incomplete type
  struct hrtimer inactive_timer;
                 ^~~~~~~~~~~~~~
make[1]: *** [kernel/time/alarmtimer.o] Error 1
make: *** [kernel/time/alarmtimer.o] Error 2

  CC      fs/timerfd.o
In file included from ./arch/powerpc/include/asm/smp.h:31,
                 from ./include/linux/smp.h:64,
                 from ./include/linux/percpu.h:7,
                 from ./include/linux/hrtimer.h:22,
                 from ./include/linux/alarmtimer.h:6,
                 from fs/timerfd.c:12:
./include/linux/sched.h:558:19: error: field 'dl_timer' has incomplete type
  struct hrtimer   dl_timer;
                   ^~~~~~~~
./include/linux/sched.h:567:17: error: field 'inactive_timer' has incomplete type
  struct hrtimer inactive_timer;
                 ^~~~~~~~~~~~~~
make[1]: *** [fs/timerfd.o] Error 1
make: *** [fs/timerfd.o] Error 2

This patch fixes it by including linux/hrtimer.h after linux/sched.h

Signed-off-by: Christophe Leroy <christophe.leroy at c-s.fr>
---
 Should it be fixed in powerpc instead ? In that case, how ? Any idea ?

 fs/timerfd.c             | 2 +-
 kernel/time/alarmtimer.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/timerfd.c b/fs/timerfd.c
index d69ad801eb80..0fc01b241382 100644
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -9,12 +9,12 @@
  *
  */
 
-#include <linux/alarmtimer.h>
 #include <linux/file.h>
 #include <linux/poll.h>
 #include <linux/init.h>
 #include <linux/fs.h>
 #include <linux/sched.h>
+#include <linux/alarmtimer.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/list.h>
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index fa5de5e8de61..5fb75c9b3f06 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -16,11 +16,11 @@
  * published by the Free Software Foundation.
  */
 #include <linux/time.h>
-#include <linux/hrtimer.h>
 #include <linux/timerqueue.h>
 #include <linux/rtc.h>
 #include <linux/sched/signal.h>
 #include <linux/sched/debug.h>
+#include <linux/hrtimer.h>
 #include <linux/alarmtimer.h>
 #include <linux/mutex.h>
 #include <linux/platform_device.h>
-- 
2.13.3