From: Samuel Neves <sneves@dei.uc.pt>
Date: Wed, 21 Feb 2018 20:50:36 +0000 (+0000)
Subject: x86/topology: Update the 'cpu cores' field in /proc/cpuinfo correctly across CPU... 
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=b8421da4b57b47dfb9ee9aacfb2612bb188f5aa5;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

x86/topology: Update the 'cpu cores' field in /proc/cpuinfo correctly across CPU hotplug operations

[ Upstream commit 4596749339e06dc7a424fc08a15eded850ed78b7 ]

Without this fix, /proc/cpuinfo will display an incorrect amount
of CPU cores, after bringing them offline and online again, as
exemplified below:

  $ cat /proc/cpuinfo | grep cores
  cpu cores	: 4
  cpu cores	: 8
  cpu cores	: 8
  cpu cores	: 20
  cpu cores	: 4
  cpu cores	: 3
  cpu cores	: 2
  cpu cores	: 2

This patch fixes this by always zeroing the booted_cores variable
upon turning off a logical CPU.

Tested-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Signed-off-by: Samuel Neves <sneves@dei.uc.pt>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: jgross@suse.com
Cc: luto@kernel.org
Cc: prarit@redhat.com
Cc: vkuznets@redhat.com
Link: http://lkml.kernel.org/r/20180221205036.5244-1-sneves@dei.uc.pt
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index cb945146b7c8..10b22fc6ef5a 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1497,6 +1497,7 @@ static void remove_siblinginfo(int cpu)
 	cpumask_clear(topology_core_cpumask(cpu));
 	c->phys_proc_id = 0;
 	c->cpu_core_id = 0;
+	c->booted_cores = 0;
 	cpumask_clear_cpu(cpu, cpu_sibling_setup_mask);
 	recompute_smt_state();
 }