linux-kernel - [RFC PATCH 3/3] sched/topology: Verify SD_* flags setup when sched

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Message-Id: <20200311183320.19186-4-valentin.schneider@arm.com>
Date:   Wed, 11 Mar 2020 18:33:20 +0000
From:   Valentin Schneider <valentin.schneider@....com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...nel.org, peterz@...radead.org, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, morten.rasmussen@....com
Subject: [RFC PATCH 3/3] sched/topology: Verify SD_* flags setup when sched_debug is on

Now that we have some description of what we expect the flags layout to
be, we can use that to assert at runtime that the actual layout is sane.

Signed-off-by: Valentin Schneider <valentin.schneider@....com>
---
 kernel/sched/topology.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index af30e2198b22..2e9aee29b3a6 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -29,6 +29,7 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
 				  struct cpumask *groupmask)
 {
 	struct sched_group *group = sd->groups;
+	int flags = sd->flags;
 
 	cpumask_clear(groupmask);
 
@@ -43,6 +44,21 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
 		printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu);
 	}
 
+	for (; flags; flags &= flags - 1) {
+		unsigned int idx = __ffs(flags);
+		unsigned int flag = BIT(idx);
+		unsigned int meta_flags = sd_flag_debug[idx].meta_flags;
+
+		if ((meta_flags & SDF_SHARED_CHILD) && sd->child &&
+		    !(sd->child->flags & flag))
+			printk(KERN_ERR "ERROR: flag %s set here but not in child\n",
+			       sd_flag_debug[idx].name);
+		else if ((meta_flags & SDF_SHARED_PARENT) && sd->parent &&
+			 !(sd->parent->flags & flag))
+			printk(KERN_ERR "ERROR: flag %s set here but not in parent\n",
+			       sd_flag_debug[idx].name);
+	}
+
 	printk(KERN_DEBUG "%*s groups:", level + 1, "");
 	do {
 		if (!group) {
-- 
2.24.0