linux-kernel - [tip:sched/core] sched/debug: Fix /proc/sched

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Message-ID: <tip-9c57259117b9c25472a3fa6d5a14d6bb3b647e87@git.kernel.org>
Date:	Wed, 8 Jun 2016 07:20:59 -0700
From:	tip-bot for Josh Poimboeuf <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	peterz@...radead.org, jpoimboe@...hat.com, hpa@...or.com,
	mingo@...nel.org, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org, mgorman@...hsingularity.net,
	srikar@...ux.vnet.ibm.com, tglx@...utronix.de,
	matt@...eblueprint.co.uk
Subject: [tip:sched/core] sched/debug: Fix /proc/sched_debug regression

Commit-ID:  9c57259117b9c25472a3fa6d5a14d6bb3b647e87
Gitweb:     http://git.kernel.org/tip/9c57259117b9c25472a3fa6d5a14d6bb3b647e87
Author:     Josh Poimboeuf <jpoimboe@...hat.com>
AuthorDate: Fri, 3 Jun 2016 17:58:40 -0500
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 8 Jun 2016 14:31:58 +0200

sched/debug: Fix /proc/sched_debug regression

Commit:

  cb2517653fcc ("sched/debug: Make schedstats a runtime tunable that is disabled by default")

... introduced a bug when CONFIG_SCHEDSTATS is enabled and the
runtime tunable is disabled (which is the default).

The wait-time, sum-exec, and sum-sleep fields are missing from the
/proc/sched_debug file in the runnable_tasks section.

Fix it with a new schedstat_val() macro which returns the field value
when schedstats is enabled and zero otherwise.  The macro works with
both SCHEDSTATS and !SCHEDSTATS.  I put the macro in stats.h since it
might end up being useful in other places.

Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Acked-by: Mel Gorman <mgorman@...hsingularity.net>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Matt Fleming <matt@...eblueprint.co.uk>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Fixes: cb2517653fcc ("sched/debug: Make schedstats a runtime tunable that is disabled by default")
Link: http://lkml.kernel.org/r/bcda7c2790cf2ccbe586a28c02dd7b6fe7749a2b.1464994423.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/debug.c | 15 ++++-----------
 kernel/sched/stats.h |  3 +++
 2 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index cf905f6..0368c39 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -427,19 +427,12 @@ print_task(struct seq_file *m, struct rq *rq, struct task_struct *p)
 		SPLIT_NS(p->se.vruntime),
 		(long long)(p->nvcsw + p->nivcsw),
 		p->prio);
-#ifdef CONFIG_SCHEDSTATS
-	if (schedstat_enabled()) {
-		SEQ_printf(m, "%9Ld.%06ld %9Ld.%06ld %9Ld.%06ld",
-			SPLIT_NS(p->se.statistics.wait_sum),
-			SPLIT_NS(p->se.sum_exec_runtime),
-			SPLIT_NS(p->se.statistics.sum_sleep_runtime));
-	}
-#else
+
 	SEQ_printf(m, "%9Ld.%06ld %9Ld.%06ld %9Ld.%06ld",
-		0LL, 0L,
+		SPLIT_NS(schedstat_val(p, se.statistics.wait_sum)),
 		SPLIT_NS(p->se.sum_exec_runtime),
-		0LL, 0L);
-#endif
+		SPLIT_NS(schedstat_val(p, se.statistics.sum_sleep_runtime)));
+
 #ifdef CONFIG_NUMA_BALANCING
 	SEQ_printf(m, " %d %d", task_node(p), task_numa_group_id(p));
 #endif
diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
index 70b3b6a..78955cb 100644
--- a/kernel/sched/stats.h
+++ b/kernel/sched/stats.h
@@ -33,6 +33,8 @@ rq_sched_info_dequeued(struct rq *rq, unsigned long long delta)
 # define schedstat_inc(rq, field)	do { if (schedstat_enabled()) { (rq)->field++; } } while (0)
 # define schedstat_add(rq, field, amt)	do { if (schedstat_enabled()) { (rq)->field += (amt); } } while (0)
 # define schedstat_set(var, val)	do { if (schedstat_enabled()) { var = (val); } } while (0)
+# define schedstat_val(rq, field)	((schedstat_enabled()) ? (rq)->field : 0)
+
 #else /* !CONFIG_SCHEDSTATS */
 static inline void
 rq_sched_info_arrive(struct rq *rq, unsigned long long delta)
@@ -47,6 +49,7 @@ rq_sched_info_depart(struct rq *rq, unsigned long long delta)
 # define schedstat_inc(rq, field)	do { } while (0)
 # define schedstat_add(rq, field, amt)	do { } while (0)
 # define schedstat_set(var, val)	do { } while (0)
+# define schedstat_val(rq, field)	0
 #endif
 
 #ifdef CONFIG_SCHED_INFO