commit b18b6a9cef7f30e9a8b7738d5fc8d568cf660855
author Nicolas Pitre <nicolas.pitre@linaro.org> Sat Jan 21 00:09:08 2017 -0500
committer John Stultz <john.stultz@linaro.org> Fri Jan 27 13:05:26 2017 -0800
tree 51be9f1d6b36120182dc4e0906460ddc1e011d65
parent 9f8197980d87a28ec3d0b3b986f770e7e7878485

timers: Omit POSIX timer stuff from task_struct when disabled

When CONFIG_POSIX_TIMERS is disabled, it is preferable to remove related
structures from struct task_struct and struct signal_struct as they
won't contain anything useful and shouldn't be relied upon by mistake.
Code still referencing those structures is also disabled here.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>

kernel/fork.c

diff --git a/kernel/fork.c b/kernel/fork.c
index 11c5c8a..105c667 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1304,6 +1304,7 @@ void __cleanup_sighand(struct sighand_struct *sighand)
 	}
 }
 
+#ifdef CONFIG_POSIX_TIMERS
 /*
  * Initialize POSIX timer handling for a thread group.
  */
@@ -1322,6 +1323,9 @@ static void posix_cpu_timers_init_group(struct signal_struct *sig)
 	INIT_LIST_HEAD(&sig->cpu_timers[1]);
 	INIT_LIST_HEAD(&sig->cpu_timers[2]);
 }
+#else
+static inline void posix_cpu_timers_init_group(struct signal_struct *sig) { }
+#endif
 
 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
 {
@@ -1346,11 +1350,11 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
 	init_waitqueue_head(&sig->wait_chldexit);
 	sig->curr_target = tsk;
 	init_sigpending(&sig->shared_pending);
-	INIT_LIST_HEAD(&sig->posix_timers);
 	seqlock_init(&sig->stats_lock);
 	prev_cputime_init(&sig->prev_cputime);
 
 #ifdef CONFIG_POSIX_TIMERS
+	INIT_LIST_HEAD(&sig->posix_timers);
 	hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 	sig->real_timer.function = it_real_fn;
 #endif
@@ -1425,6 +1429,7 @@ static void rt_mutex_init_task(struct task_struct *p)
 #endif
 }
 
+#ifdef CONFIG_POSIX_TIMERS
 /*
  * Initialize POSIX timer handling for a single task.
  */
@@ -1437,6 +1442,9 @@ static void posix_cpu_timers_init(struct task_struct *tsk)
 	INIT_LIST_HEAD(&tsk->cpu_timers[1]);
 	INIT_LIST_HEAD(&tsk->cpu_timers[2]);
 }
+#else
+static inline void posix_cpu_timers_init(struct task_struct *tsk) { }
+#endif
 
 static inline void
 init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)