Messages in this thread Patch in this message | | | From | Sasha Levin <> | Subject | [PATCH AUTOSEL 4.14 35/37] xen/manage: don't complain about an empty value in control/sysrq node | Date | Mon, 1 Oct 2018 00:39:14 +0000 |
| |
From: Vitaly Kuznetsov <vkuznets@redhat.com>
[ Upstream commit 87dffe86d406bee8782cac2db035acb9a28620a7 ]
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> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> --- drivers/xen/manage.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c index 587d12829925..0444ebdda3f0 100644 --- a/drivers/xen/manage.c +++ b/drivers/xen/manage.c @@ -283,9 +283,11 @@ 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); -- 2.17.1
| |