linux-kernel - [PATCH] xen: don't print error message in case of missing Xenstore entry

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Date:   Mon, 29 May 2017 11:13:39 +0200
From:   Juergen Gross <jgross@...e.com>
To:     linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org
Cc:     boris.ostrovsky@...cle.com, Juergen Gross <jgross@...e.com>
Subject: [PATCH] xen: don't print error message in case of missing Xenstore entry

When registering for the Xenstore watch of the node control/sysrq the
handler will be called at once. Don't issue an error message if the
Xenstore node isn't there, as it will be created only when an event
is being triggered.

Signed-off-by: Juergen Gross <jgross@...e.com>
---
 drivers/xen/manage.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index c1ec8ee80924..7ddd0803da23 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -277,8 +277,11 @@ static void sysrq_handler(struct xenbus_watch *watch, const char *path,
 	err = xenbus_transaction_start(&xbt);
 	if (err)
 		return;
-	if (xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key) < 0) {
-		pr_err("Unable to read sysrq code in control/sysrq\n");
+	err = xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key);
+	if (err < 0) {
+		if (err != -ENOENT)
+			pr_err("Error %d reading sysrq code in control/sysrq\n",
+			       err);
 		xenbus_transaction_end(xbt, 1);
 		return;
 	}
-- 
2.12.3