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

["Jan H. Schönherr" <jschoenh@amazon.de>]

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@amazon.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