linux-kernel - [PATCH 07/13] openrisc: fix initial preempt state for secondary cpu tasks

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Message-Id: <b717771fb3be766953bf1af3e8782b9a29472848.1504129273.git.shorne@gmail.com>
Date:   Thu, 31 Aug 2017 07:02:11 +0900
From:   Stafford Horne <shorne@...il.com>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Openrisc <openrisc@...ts.librecores.org>,
        Stafford Horne <shorne@...il.com>,
        Jonas Bonn <jonas@...thpole.se>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        Jan Henrik Weinstock <jan.weinstock@....rwth-aachen.de>
Subject: [PATCH 07/13] openrisc: fix initial preempt state for secondary cpu tasks

During SMP testing we were getting the below warning after booting the
secondary cpu:

[    0.060000] BUG: scheduling while atomic: swapper/1/0/0x00000000

This change follows similar patterns from other architectures to start
the schduler with preempt disabled.

Signed-off-by: Stafford Horne <shorne@...il.com>
---
 arch/openrisc/include/asm/thread_info.h | 2 +-
 arch/openrisc/kernel/smp.c              | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/openrisc/include/asm/thread_info.h b/arch/openrisc/include/asm/thread_info.h
index 6e619a79a401..c229aa6bb502 100644
--- a/arch/openrisc/include/asm/thread_info.h
+++ b/arch/openrisc/include/asm/thread_info.h
@@ -74,7 +74,7 @@ struct thread_info {
 	.task		= &tsk,				\
 	.flags		= 0,				\
 	.cpu		= 0,				\
-	.preempt_count	= 1,				\
+	.preempt_count	= INIT_PREEMPT_COUNT,		\
 	.addr_limit	= KERNEL_DS,			\
 	.ksp            = 0,                            \
 }
diff --git a/arch/openrisc/kernel/smp.c b/arch/openrisc/kernel/smp.c
index ae93b84062ff..24f7aa45b0ba 100644
--- a/arch/openrisc/kernel/smp.c
+++ b/arch/openrisc/kernel/smp.c
@@ -125,6 +125,7 @@ asmlinkage __init void secondary_start_kernel(void)
 
 	local_irq_enable();
 
+	preempt_disable();
 	/*
 	 * OK, it's off to the idle thread for us
 	 */
-- 
2.13.5