[PATCH v0 01/42] x86: Check notifier registration return value

[Borislav Petkov]

From: Borislav Petkov <bp@xxxxxxx>

Avoid homegrown notifier registration checks.

No functional changes.

Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: x86@xxxxxxxxxx
---
 arch/x86/kernel/cpu/mce/core.c       | 3 ++-
 arch/x86/kernel/cpu/mce/dev-mcelog.c | 3 ++-
 arch/x86/kernel/setup.c              | 7 +++++--
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 6ed365337a3b..2c4a9ff49384 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -164,7 +164,8 @@ void mce_register_decode_chain(struct notifier_block *nb)
 		    nb->priority > MCE_PRIO_HIGHEST))
 		return;
 
-	blocking_notifier_chain_register(&x86_mce_decoder_chain, nb);
+	if (blocking_notifier_chain_register(&x86_mce_decoder_chain, nb))
+		pr_warn("MCE decoder chain notifier already registered\n");
 }
 EXPORT_SYMBOL_GPL(mce_register_decode_chain);
 
diff --git a/arch/x86/kernel/cpu/mce/dev-mcelog.c b/arch/x86/kernel/cpu/mce/dev-mcelog.c
index 100fbeebdc72..efa503a512dd 100644
--- a/arch/x86/kernel/cpu/mce/dev-mcelog.c
+++ b/arch/x86/kernel/cpu/mce/dev-mcelog.c
@@ -281,7 +281,8 @@ static long mce_chrdev_ioctl(struct file *f, unsigned int cmd,
 
 void mce_register_injector_chain(struct notifier_block *nb)
 {
-	blocking_notifier_chain_register(&mce_injector_chain, nb);
+	if (blocking_notifier_chain_register(&mce_injector_chain, nb))
+		pr_warn("MCE injector notifier already registered\n");
 }
 EXPORT_SYMBOL_GPL(mce_register_injector_chain);
 
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 40ed44ead063..e28cd4dd81c1 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1245,8 +1245,11 @@ static struct notifier_block kernel_offset_notifier = {
 
 static int __init register_kernel_offset_dumper(void)
 {
-	atomic_notifier_chain_register(&panic_notifier_list,
-					&kernel_offset_notifier);
+	int ret = atomic_notifier_chain_register(&panic_notifier_list,
+						 &kernel_offset_notifier);
+	if (ret)
+		pr_warn("Kernel offset dumper notifier already registered\n");
+
 	return 0;
 }
 __initcall(register_kernel_offset_dumper);
-- 
2.29.2