[v0,18/42] drivers/xen: Check notifier registration return value

Commit Message

Borislav Petkov Nov. 8, 2021, 10:11 a.m. UTC

From: Borislav Petkov <[e-mail]>

Avoid homegrown notifier registration checks.

No functional changes.

Signed-off-by: Borislav Petkov <[e-mail]>
Cc: [e-mail]
---
 drivers/xen/manage.c              | 3 ++-
 drivers/xen/xenbus/xenbus_probe.c | 8 +++++---
 2 files changed, 7 insertions(+), 4 deletions(-)

Patch

diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index 374d36de7f5a..f3c5cef0995f 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -48,7 +48,8 @@  static RAW_NOTIFIER_HEAD(xen_resume_notifier);
 
 void xen_resume_notifier_register(struct notifier_block *nb)
 {
-	raw_notifier_chain_register(&xen_resume_notifier, nb);
+	if (raw_notifier_chain_register(&xen_resume_notifier, nb))
+		pr_warn("Xen resume notifier already registered\n");
 }
 EXPORT_SYMBOL_GPL(xen_resume_notifier_register);
 
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index bd003ca8acbe..4e83ce95acd1 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -731,10 +731,12 @@  int register_xenstore_notifier(struct notifier_block *nb)
 {
 	int ret = 0;
 
-	if (xenstored_ready > 0)
+	if (xenstored_ready > 0) {
 		ret = nb->notifier_call(nb, 0, NULL);
-	else
-		blocking_notifier_chain_register(&xenstore_chain, nb);
+	} else {
+		if (blocking_notifier_chain_register(&xenstore_chain, nb))
+			pr_warn("Xenstore notifier already registered\n");
+	}
 
 	return ret;
 }