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>

diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 1f8c06c..6ed8812 100644 (file)
--- 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 9c2d46d..4f92a23 100644 (file)
--- 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)

diff --git a/kernel/sched.c b/kernel/sched.c
index b646dad..3925a1b 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2595,7 +2595,9 @@ void sched_fork(struct task_struct *p, int clone_flags)
        /* Want to start with kernel preemption disabled. */
        task_thread_info(p)->preempt_count = 1;
 #endif
+#ifdef CONFIG_SMP
        plist_node_init(&p->pushable_tasks, MAX_PRIO);
+#endif
 
        put_cpu();
 }