linux-kernel - [PATCH v2 4/6] x86/mce: Allow a variable number of internal MCE decode notifiers

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Date:   Fri,  3 Jan 2020 16:07:20 +0100
From:   Jan H. Schönherr <jschoenh@...zon.de>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Jan H. Schönherr <jschoenh@...zon.de>,
        Yazen Ghannam <yazen.ghannam@....com>,
        linux-kernel@...r.kernel.org, linux-edac@...r.kernel.org,
        Tony Luck <tony.luck@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Subject: [PATCH v2 4/6] x86/mce: Allow a variable number of internal MCE decode notifiers

Get rid of the compile time constant of internal (or mandatory)
MCE decode notifiers in preparation for future changes. Instead,
distinguish explicitly between internal and external MCE decode
notifiers.

Signed-off-by: Jan H. Schönherr <jschoenh@...zon.de>
---
New in v2, preparation for patches 5 and 6.
---
 arch/x86/kernel/cpu/mce/core.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 1d91ce956772..d48deb127071 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -157,21 +157,24 @@ 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
+ * We run the default notifier as long as we have no external
  * notifiers registered on the chain.
  */
-#define NUM_DEFAULT_NOTIFIERS	3
 static atomic_t num_notifiers;
 
-void mce_register_decode_chain(struct notifier_block *nb)
+static void mce_register_decode_chain_internal(struct notifier_block *nb)
 {
 	if (WARN_ON(nb->priority > MCE_PRIO_MCELOG && nb->priority < MCE_PRIO_EDAC))
 		return;
 
+	blocking_notifier_chain_register(&x86_mce_decoder_chain, nb);
+}
+
+void mce_register_decode_chain(struct notifier_block *nb)
+{
 	atomic_inc(&num_notifiers);
 
-	blocking_notifier_chain_register(&x86_mce_decoder_chain, nb);
+	mce_register_decode_chain_internal(nb);
 }
 EXPORT_SYMBOL_GPL(mce_register_decode_chain);
 
@@ -611,7 +614,7 @@ 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)
+	if (atomic_read(&num_notifiers))
 		return NOTIFY_DONE;
 
 	__print_mce(m);
@@ -1966,9 +1969,9 @@ __setup("mce", mcheck_enable);
 int __init mcheck_init(void)
 {
 	mcheck_intel_therm_init();
-	mce_register_decode_chain(&first_nb);
-	mce_register_decode_chain(&mce_uc_nb);
-	mce_register_decode_chain(&mce_default_nb);
+	mce_register_decode_chain_internal(&first_nb);
+	mce_register_decode_chain_internal(&mce_uc_nb);
+	mce_register_decode_chain_internal(&mce_default_nb);
 	mcheck_vendor_init_severity();
 
 	INIT_WORK(&mce_work, mce_gen_pool_process);
-- 
2.22.0.3.gb49bb57c8208.dirty