sched: Make pushable_tasks CONFIG_SMP dependant

As noted by Peter Zijlstra at https://lkml.org/lkml/2010/11/10/391
(while reviewing other stuff, though), tracking pushable tasks
only makes sense on SMP systems.

Signed-off-by: Dario Faggioli <raistlin@linux.it>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Gregory Haskins <ghaskins@novell.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1291143093.2697.298.camel@Palantir>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 10 insertions, 1 deletions

diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 1f8c06ce0fa6..6ed8812bfe2d 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -12,6 +12,13 @@
 #include <linux/securebits.h>
 #include <net/net_namespace.h>
 
+#ifdef CONFIG_SMP
+# define INIT_PUSHABLE_TASKS(tsk)                                       \
+        .pushable_tasks = PLIST_NODE_INIT(tsk.pushable_tasks, MAX_PRIO),
+#else
+# define INIT_PUSHABLE_TASKS(tsk)
+#endif
+
 extern struct files_struct init_files;
 extern struct fs_struct init_fs;
 
@@ -137,7 +144,7 @@ extern struct cred init_cred;
                 .nr_cpus_allowed = NR_CPUS,                             \
         },                                                              \
         .tasks          = LIST_HEAD_INIT(tsk.tasks),                    \
-        .pushable_tasks = PLIST_NODE_INIT(tsk.pushable_tasks, MAX_PRIO), \
+        INIT_PUSHABLE_TASKS(tsk)                                        \
         .ptraced        = LIST_HEAD_INIT(tsk.ptraced),                  \
         .ptrace_entry   = LIST_HEAD_INIT(tsk.ptrace_entry),             \
         .real_parent    = &tsk,                                         \
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 9c2d46da486e..4f92a239c14d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1240,7 +1240,9 @@ struct task_struct {
 #endif
 
         struct list_head tasks;
+#ifdef CONFIG_SMP
         struct plist_node pushable_tasks;
+#endif
 
         struct mm_struct *mm, *active_mm;
 #if defined(SPLIT_RSS_COUNTING)