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Commit 8d9560eb authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Greg Kroah-Hartman
Browse files

Drivers: hv: kvp,vss: Fast propagation of userspace communication failure 



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: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 64914207

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;