From: Johnlay Park <jonglae.park@samsung.com>
Date: Mon, 19 Feb 2018 05:51:23 +0000 (+0900)
Subject: [COMMON] sched/fair: Fix hang during rebuilding sd in compute_energy.
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=9afacaea65f3e0140cef59bdb643aad147748b22;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git

[COMMON] sched/fair: Fix hang during rebuilding sd in compute_energy.

This patch implemtes the hotplug race check differently and
should therefore reinstate support for per-cpu capacity states.

refer the commit d5f2ca8a4778938c45d679d67c45b256114de3c5,
64f6fd103dadaf762d3dc11173c5544ff6ec1b16.

Change-Id: Iab48cf63c3672e10ad8230d1eeb09185ea588022
Signed-off-by: Johnlay Park <jonglae.park@samsung.com>
---

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ddbf7eeefcc0..bc6ce0bc170e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5867,7 +5867,17 @@ static int compute_energy(struct energy_env *eenv)
 
 			} while (sg = sg->next, sg != sd->groups);
 		}
+
+		/*
+		 * If we raced with hotplug and got an sd NULL-pointer;
+		 * returning a wrong energy estimation is better than
+		 * entering an infinite loop.
+		 */
+		if (cpumask_test_cpu(cpu, &visit_cpus))
+			return -EINVAL;
+
 next_cpu:
+		cpumask_clear_cpu(cpu, &visit_cpus);
 		continue;
 	}