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

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>
(cherry picked from commit 4596749339e06dc7a424fc08a15eded850ed78b7)

Orabug: 28933009

Signed-off-by: Honglei Wang <honglei.wang@oracle.com>
Reviewed-by: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 20b0f575da96e058d6f703b027f02e89bf1d3195..6af203bc359308a566dd3cfafc4ac545662731fc 100644 (file)
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1376,6 +1376,7 @@ static void remove_siblinginfo(int cpu)
        cpumask_clear(cpu_core_mask(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();
 }