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authorVitaly Kuznetsov <vkuznets@redhat.com>2018-09-06 13:26:08 +0200
committerBoris Ostrovsky <boris.ostrovsky@oracle.com>2018-09-14 08:51:10 -0400
commit87dffe86d406bee8782cac2db035acb9a28620a7 (patch)
treeee0ab909b1280f621dad908ac4a65f2765ca9371
parent11da3a7f84f19c26da6f86af878298694ede0804 (diff)
xen/manage: don't complain about an empty value in control/sysrq node
When guest receives a sysrq request from the host it acknowledges it by writing '\0' to control/sysrq xenstore node. This, however, make xenstore watch fire again but xenbus_scanf() fails to parse empty value with "%c" format string: sysrq: SysRq : Emergency Sync Emergency Sync complete xen:manage: Error -34 reading sysrq code in control/sysrq Ignore -ERANGE the same way we already ignore -ENOENT, empty value in control/sysrq is totally legal. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Wei Liu <wei.liu2@citrix.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
-rw-r--r--drivers/xen/manage.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index c93d8ef8df34..5bb01a62f214 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -280,9 +280,11 @@ static void sysrq_handler(struct xenbus_watch *watch, const char *path,
/*
* The Xenstore watch fires directly after registering it and
* after a suspend/resume cycle. So ENOENT is no error but
- * might happen in those cases.
+ * might happen in those cases. ERANGE is observed when we get
+ * an empty value (''), this happens when we acknowledge the
+ * request by writing '\0' below.
*/
- if (err != -ENOENT)
+ if (err != -ENOENT && err != -ERANGE)
pr_err("Error %d reading sysrq code in control/sysrq\n",
err);
xenbus_transaction_end(xbt, 1);