From 8d9560ebcc6448472b3afe8f36f37d6b0de8f5a4 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Thu, 6 Nov 2014 18:21:25 +0100 Subject: [PATCH] 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: Vitaly Kuznetsov Signed-off-by: Greg Kroah-Hartman --- drivers/hv/hv_kvp.c | 9 ++++++++- drivers/hv/hv_snapshot.c | 8 +++++++- 2 files changed, 15 insertions(+), 2 deletions(-) diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c index 521c14625b3a..beb8105c0e7b 100644 --- a/drivers/hv/hv_kvp.c +++ b/drivers/hv/hv_kvp.c @@ -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; diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c index 21e51be74e6c..9d5e0d1efdb5 100644 --- a/drivers/hv/hv_snapshot.c +++ b/drivers/hv/hv_snapshot.c @@ -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;