linux-kernel - [PATCH] arch/x86: Initialize __max_smt

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Date:   Wed,  6 Dec 2017 07:56:08 -0500
From:   Prarit Bhargava <prarit@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Prarit Bhargava <prarit@...hat.com>,
        Jakub Kicinski <kubakici@...pl>, netdev@...r.kernel.org,
        Clark Williams <williams@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH] arch/x86: Initialize __max_smt_threads to 1

A single socket, single core, single thread system has __max_smt_threads
set to 0 since smp_callin() is not called.

__max_smt_threads must be a minimum of 1.

Fixes: b1cbacc8663a ("x86/smpboot: Do not use smp_num_siblings in __max_logical_packages calculation)
Signed-off-by: Prarit Bhargava <prarit@...hat.com>
Cc: Jakub Kicinski <kubakici@...pl>
Cc: netdev@...r.kernel.org
Cc: "netdev@...r.kernel.org"
Cc: Clark Williams <williams@...hat.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: x86@...nel.org
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: https://marc.info/?t=151246092100004&r=1&w=2
---
 arch/x86/kernel/smpboot.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index eaee15fb7d8b..882c61e1d7a2 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -106,7 +106,7 @@ EXPORT_SYMBOL(__max_logical_packages);
 static unsigned int logical_packages __read_mostly;
 
 /* Maximum number of SMT threads on any online core */
-int __max_smt_threads __read_mostly;
+int __read_mostly __max_smt_threads = 1;
 
 /* Flag to indicate if a complete sched domain rebuild is required */
 bool x86_topology_update;
-- 
2.15.0.rc0.39.g2f0e14e64