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

[Borislav Petkov <bp@xxxxxxxxx>]

From: Borislav Petkov <bp@xxxxxxx>

Avoid homegrown notifier registration checks.

No functional changes.

Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
---
 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