linux-kernel - [tip: ras/core] x86/mce: Change default MCE logger to check mce->kflags

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Date:   Wed, 15 Apr 2020 09:49:47 -0000
From:   "tip-bot2 for Tony Luck" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Tony Luck <tony.luck@...el.com>, Borislav Petkov <bp@...e.de>,
        x86 <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [tip: ras/core] x86/mce: Change default MCE logger to check mce->kflags

The following commit has been merged into the ras/core branch of tip:

Commit-ID:     925946cfa715a5a71639528f82b98e58f14dd4cb
Gitweb:        https://git.kernel.org/tip/925946cfa715a5a71639528f82b98e58f14dd4cb
Author:        Tony Luck <tony.luck@...el.com>
AuthorDate:    Fri, 14 Feb 2020 14:27:18 -08:00
Committer:     Borislav Petkov <bp@...e.de>
CommitterDate: Tue, 14 Apr 2020 15:59:57 +02:00

x86/mce: Change default MCE logger to check mce->kflags

Instead of keeping count of how many handlers are registered on the
MCE notifier chain and printing if below some magic value, look at
mce->kflags to see if anyone claims to have handled/logged this error.

 [ bp: Do not print ->kflags in __print_mce(). ]

Signed-off-by: Tony Luck <tony.luck@...el.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Tested-by: Tony Luck <tony.luck@...el.com>
Link: https://lkml.kernel.org/r/20200214222720.13168-6-tony.luck@intel.com
---
 arch/x86/kernel/cpu/mce/core.c | 19 +++----------------
 1 file changed, 3 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 5666a48..fc879b6 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -158,29 +158,17 @@ void mce_log(struct mce *m)
 }
 EXPORT_SYMBOL_GPL(mce_log);
 
-/*
- * We run the default notifier if we have only the UC, the first and the
- * default notifier registered. I.e., the mandatory NUM_DEFAULT_NOTIFIERS
- * notifiers registered on the chain.
- */
-#define NUM_DEFAULT_NOTIFIERS	3
-static atomic_t num_notifiers;
-
 void mce_register_decode_chain(struct notifier_block *nb)
 {
 	if (WARN_ON(nb->priority > MCE_PRIO_MCELOG && nb->priority < MCE_PRIO_EDAC))
 		return;
 
-	atomic_inc(&num_notifiers);
-
 	blocking_notifier_chain_register(&x86_mce_decoder_chain, nb);
 }
 EXPORT_SYMBOL_GPL(mce_register_decode_chain);
 
 void mce_unregister_decode_chain(struct notifier_block *nb)
 {
-	atomic_dec(&num_notifiers);
-
 	blocking_notifier_chain_unregister(&x86_mce_decoder_chain, nb);
 }
 EXPORT_SYMBOL_GPL(mce_unregister_decode_chain);
@@ -263,6 +251,7 @@ static void __print_mce(struct mce *m)
 	}
 
 	pr_cont("\n");
+
 	/*
 	 * Note this output is parsed by external tools and old fields
 	 * should not be changed.
@@ -602,10 +591,8 @@ static int mce_default_notifier(struct notifier_block *nb, unsigned long val,
 	if (!m)
 		return NOTIFY_DONE;
 
-	if (atomic_read(&num_notifiers) > NUM_DEFAULT_NOTIFIERS)
-		return NOTIFY_DONE;
-
-	__print_mce(m);
+	if (!m->kflags)
+		__print_mce(m);
 
 	return NOTIFY_DONE;
 }