Drivers: hv: kvp,vss: Fast propagation of userspace communication failure (8d9560eb) · Commits · 戴 / test

If we fail to send a message to userspace daemon with cn_netlink_send() there is no need to wait for userspace to reply as it is not going to happen. This happens when kvp or vss daemon is stopped after a successful handshake. Report HV_E_FAIL immediately and cancel the timeout job so host won't receive two failures. Use pr_warn() for VSS and pr_debug() for KVP deliberately as VSS request are rare and result in a failed backup. KVP requests are much more frequent after a successful handshake so avoid flooding logs. It would be nice to have an ability to de-negotiate with the host in case userspace daemon gets disconnected so we won't receive new requests. But I'm not sure it is possible. Signed-off-by:

Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/hv_kvp.c

+8 −1

Original line number	Diff line number	Diff line
		@@ -350,6 +350,7 @@ kvp_send_key(struct work_struct *dummy)
		__u8 pool = kvp_transaction.kvp_msg->kvp_hdr.pool;
		__u32 val32;
		__u64 val64;
		int rc;

		msg = kzalloc(sizeof(*msg) + sizeof(struct hv_kvp_msg) , GFP_ATOMIC);
		if (!msg)
		@@ -446,7 +447,13 @@ kvp_send_key(struct work_struct *dummy)
		}

		msg->len = sizeof(struct hv_kvp_msg);
		cn_netlink_send(msg, 0, 0, GFP_ATOMIC);
		rc = cn_netlink_send(msg, 0, 0, GFP_ATOMIC);
		if (rc) {
		pr_debug("KVP: failed to communicate to the daemon: %d\n", rc);
		if (cancel_delayed_work_sync(&kvp_work))
		kvp_respond_to_host(message, HV_E_FAIL);
		}

		kfree(msg);

		return;

drivers/hv/hv_snapshot.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -96,6 +96,7 @@ vss_cn_callback(struct cn_msg msg, struct netlink_skb_parms nsp)
		static void vss_send_op(struct work_struct *dummy)
		{
		int op = vss_transaction.msg->vss_hdr.operation;
		int rc;
		struct cn_msg *msg;
		struct hv_vss_msg *vss_msg;

		@@ -111,7 +112,12 @@ static void vss_send_op(struct work_struct *dummy)
		vss_msg->vss_hdr.operation = op;
		msg->len = sizeof(struct hv_vss_msg);

		cn_netlink_send(msg, 0, 0, GFP_ATOMIC);
		rc = cn_netlink_send(msg, 0, 0, GFP_ATOMIC);
		if (rc) {
		pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
		if (cancel_delayed_work_sync(&vss_timeout_work))
		vss_respond_to_host(HV_E_FAIL);
		}
		kfree(msg);

		return;

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