linux-kernel - [PATCH v0 18/42] drivers/xen: Check notifier registration return value

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Message-Id: <20211108101157.15189-19-bp@alien8.de>
Date:   Mon,  8 Nov 2021 11:11:33 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     xen-devel@...ts.xenproject.org
Subject: [PATCH v0 18/42] drivers/xen: Check notifier registration return value

From: Borislav Petkov <bp@...e.de>

Avoid homegrown notifier registration checks.

No functional changes.

Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: xen-devel@...ts.xenproject.org
---
 drivers/xen/manage.c              | 3 ++-
 drivers/xen/xenbus/xenbus_probe.c | 8 +++++---
 2 files changed, 7 insertions(+), 4 deletions(-)

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;
 }
-- 
2.29.2