linux-kernel - [PATCH 6/6] x86/mce: Do not register notifiers with invalid prio

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Message-Id: <20170327093304.10683-7-bp@alien8.de>
Date:   Mon, 27 Mar 2017 11:33:04 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     X86 ML <x86@...nel.org>
Cc:     linux-edac <linux-edac@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 6/6] x86/mce: Do not register notifiers with invalid prio

From: Borislav Petkov <bp@...e.de>

This is just a defensive precaution: do not register notifiers with a
priority which would disrupt the error handling in the notifiers with
prio higher than MCE_PRIO_EDAC.

Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/kernel/cpu/mcheck/mce.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 8e119156429b..4b57b8336ecd 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -157,9 +157,10 @@ static atomic_t num_notifiers;
 
 void mce_register_decode_chain(struct notifier_block *nb)
 {
-	atomic_inc(&num_notifiers);
+	if (WARN_ON(nb->priority > MCE_PRIO_LOWEST && nb->priority < MCE_PRIO_EDAC))
+		return;
 
-	WARN_ON(nb->priority > MCE_PRIO_LOWEST && nb->priority < MCE_PRIO_EDAC);
+	atomic_inc(&num_notifiers);
 
 	atomic_notifier_chain_register(&x86_mce_decoder_chain, nb);
 }
-- 
2.11.0