sched/stat: Simplify the sched_info accounting dependency

Both CONFIG_SCHEDSTATS=y and CONFIG_TASK_DELAY_ACCT=y track task
sched_info, which results in ugly #if clauses.

Simplify the code by introducing a synthethic CONFIG_SCHED_INFO
switch, selected by both.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: a.p.zijlstra@chello.nl
Cc: ricklind@us.ibm.com
Link: http://lkml.kernel.org/r/8d19eef800811a94b0f91bcbeb27430a884d7433.1435255405.git.naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

5 files changed, 12 insertions, 6 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6633e83e608a..9bf4bc0e3b8b 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -849,7 +849,7 @@ extern struct user_struct root_user;
 struct backing_dev_info;
 struct reclaim_state;
 
-#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
+#ifdef CONFIG_SCHED_INFO
 struct sched_info {
         /* cumulative counters */
         unsigned long pcount;         /* # of times run on this cpu */
@@ -859,7 +859,7 @@ struct sched_info {
         unsigned long long last_arrival,/* when we last ran on a cpu */
                            last_queued; /* when we were last queued to run */
 };
-#endif /* defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) */
+#endif /* CONFIG_SCHED_INFO */
 
 #ifdef CONFIG_TASK_DELAY_ACCT
 struct task_delay_info {
@@ -1408,7 +1408,7 @@ struct task_struct {
         int rcu_tasks_idle_cpu;
 #endif /* #ifdef CONFIG_TASKS_RCU */
 
-#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
+#ifdef CONFIG_SCHED_INFO
         struct sched_info sched_info;
 #endif
 
diff --git a/init/Kconfig b/init/Kconfig
index b999fa381bf9..12cb556ad160 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -435,6 +435,7 @@ config TASKSTATS
 config TASK_DELAY_ACCT
         bool "Enable per-task delay accounting"
         depends on TASKSTATS
+        select SCHED_INFO
         help
           Collect information on time spent by a task waiting for system
           resources like cpu, synchronous block I/O completion and swapping
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index c86935a7f1f8..abb8785ed1ba 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1975,7 +1975,7 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
         set_task_cpu(p, cpu);
         raw_spin_unlock_irqrestore(&p->pi_lock, flags);
 
-#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
+#ifdef CONFIG_SCHED_INFO
         if (likely(sched_info_on()))
                 memset(&p->sched_info, 0, sizeof(p->sched_info));
 #endif
diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
index 077ebbd5e10f..b0fbc7632de5 100644
--- a/kernel/sched/stats.h
+++ b/kernel/sched/stats.h
@@ -47,7 +47,7 @@ rq_sched_info_depart(struct rq *rq, unsigned long long delta)
 # define schedstat_set(var, val)        do { } while (0)
 #endif
 
-#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
+#ifdef CONFIG_SCHED_INFO
 static inline void sched_info_reset_dequeued(struct task_struct *t)
 {
         t->sched_info.last_queued = 0;
@@ -156,7 +156,7 @@ sched_info_switch(struct rq *rq,
 #define sched_info_depart(rq, t)                do { } while (0)
 #define sched_info_arrive(rq, next)             do { } while (0)
 #define sched_info_switch(rq, t, next)          do { } while (0)
-#endif /* CONFIG_SCHEDSTATS || CONFIG_TASK_DELAY_ACCT */
+#endif /* CONFIG_SCHED_INFO */
 
 /*
  * The following are functions that support scheduler-internal time accounting.
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index b908048f8d6a..e2894b23efb6 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -841,9 +841,14 @@ config SCHED_DEBUG
           that can help debug the scheduler. The runtime overhead of this
           option is minimal.
 
+config SCHED_INFO
+        bool
+        default n
+
 config SCHEDSTATS
         bool "Collect scheduler statistics"
         depends on DEBUG_KERNEL && PROC_FS
+        select SCHED_INFO
         help
           If you say Y here, additional code will be inserted into the
           scheduler and related routines to collect statistics about