diff options
| -rw-r--r-- | drivers/hv/hv_snapshot.c | 87 |
1 files changed, 58 insertions, 29 deletions
diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c index 4bb9b1c63cac..ddb1cda4b2fc 100644 --- a/drivers/hv/hv_snapshot.c +++ b/drivers/hv/hv_snapshot.c @@ -33,16 +33,21 @@ #define VSS_USERSPACE_TIMEOUT (msecs_to_jiffies(10 * 1000)) /* - * Global state maintained for transaction that is being processed. - * Note that only one transaction can be active at any point in time. + * Global state maintained for transaction that is being processed. For a class + * of integration services, including the "VSS service", the specified protocol + * is a "request/response" protocol which means that there can only be single + * outstanding transaction from the host at any given point in time. We use + * this to simplify memory management in this driver - we cache and process + * only one message at a time. * - * This state is set when we receive a request from the host; we - * cleanup this state when the transaction is completed - when we respond - * to the host with the key value. + * While the request/response protocol is guaranteed by the host, we further + * ensure this by serializing packet processing in this driver - we do not + * read additional packets from the VMBUs until the current packet is fully + * handled. */ static struct { - bool active; /* transaction status - active or not */ + int state; /* hvutil_device_state */ int recv_len; /* number of bytes received. */ struct vmbus_channel *recv_channel; /* chn we got the request */ u64 recv_req_id; /* request ID. */ @@ -75,6 +80,10 @@ static void vss_timeout_func(struct work_struct *dummy) pr_warn("VSS: timeout waiting for daemon to reply\n"); vss_respond_to_host(HV_E_FAIL); + /* Transaction is finished, reset the state. */ + if (vss_transaction.state > HVUTIL_READY) + vss_transaction.state = HVUTIL_READY; + hv_poll_channel(vss_transaction.vss_context, hv_vss_onchannelcallback); } @@ -86,15 +95,32 @@ vss_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp) vss_msg = (struct hv_vss_msg *)msg->data; - if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER) { + /* + * Don't process registration messages if we're in the middle of + * a transaction processing. + */ + if (vss_transaction.state > HVUTIL_READY && + vss_msg->vss_hdr.operation == VSS_OP_REGISTER) + return; + + if (vss_transaction.state == HVUTIL_DEVICE_INIT && + vss_msg->vss_hdr.operation == VSS_OP_REGISTER) { pr_info("VSS daemon registered\n"); - vss_transaction.active = false; + vss_transaction.state = HVUTIL_READY; + } else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) { + vss_transaction.state = HVUTIL_USERSPACE_RECV; + if (cancel_delayed_work_sync(&vss_timeout_work)) { + vss_respond_to_host(vss_msg->error); + /* Transaction is finished, reset the state. */ + vss_transaction.state = HVUTIL_READY; + hv_poll_channel(vss_transaction.vss_context, + hv_vss_onchannelcallback); + } + } else { + /* This is a spurious call! */ + pr_warn("VSS: Transaction not active\n"); + return; } - if (cancel_delayed_work_sync(&vss_timeout_work)) - vss_respond_to_host(vss_msg->error); - - hv_poll_channel(vss_transaction.vss_context, - hv_vss_onchannelcallback); } @@ -105,6 +131,10 @@ static void vss_send_op(struct work_struct *dummy) struct cn_msg *msg; struct hv_vss_msg *vss_msg; + /* The transaction state is wrong. */ + if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED) + return; + msg = kzalloc(sizeof(*msg) + sizeof(*vss_msg), GFP_ATOMIC); if (!msg) return; @@ -117,12 +147,16 @@ static void vss_send_op(struct work_struct *dummy) vss_msg->vss_hdr.operation = op; msg->len = sizeof(struct hv_vss_msg); + vss_transaction.state = HVUTIL_USERSPACE_REQ; 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)) + if (cancel_delayed_work_sync(&vss_timeout_work)) { vss_respond_to_host(HV_E_FAIL); + vss_transaction.state = HVUTIL_READY; + } } + kfree(msg); return; @@ -141,17 +175,6 @@ vss_respond_to_host(int error) u64 req_id; /* - * If a transaction is not active; log and return. - */ - - if (!vss_transaction.active) { - /* - * This is a spurious call! - */ - pr_warn("VSS: Transaction not active\n"); - return; - } - /* * Copy the global state for completing the transaction. Note that * only one transaction can be active at a time. */ @@ -159,7 +182,6 @@ vss_respond_to_host(int error) buf_len = vss_transaction.recv_len; channel = vss_transaction.recv_channel; req_id = vss_transaction.recv_req_id; - vss_transaction.active = false; icmsghdrp = (struct icmsg_hdr *) &recv_buffer[sizeof(struct vmbuspipe_hdr)]; @@ -196,7 +218,7 @@ void hv_vss_onchannelcallback(void *context) struct icmsg_hdr *icmsghdrp; struct icmsg_negotiate *negop = NULL; - if (vss_transaction.active) { + if (vss_transaction.state > HVUTIL_READY) { /* * We will defer processing this callback once * the current transaction is complete. @@ -230,7 +252,6 @@ void hv_vss_onchannelcallback(void *context) vss_transaction.recv_len = recvlen; vss_transaction.recv_channel = channel; vss_transaction.recv_req_id = requestid; - vss_transaction.active = true; vss_transaction.msg = (struct hv_vss_msg *)vss_msg; switch (vss_msg->vss_hdr.operation) { @@ -247,6 +268,12 @@ void hv_vss_onchannelcallback(void *context) */ case VSS_OP_FREEZE: case VSS_OP_THAW: + if (vss_transaction.state < HVUTIL_READY) { + /* Userspace is not registered yet */ + vss_respond_to_host(HV_E_FAIL); + return; + } + vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED; schedule_work(&vss_send_op_work); schedule_delayed_work(&vss_timeout_work, VSS_USERSPACE_TIMEOUT); @@ -297,12 +324,14 @@ hv_vss_init(struct hv_util_service *srv) * Defer processing channel callbacks until the daemon * has registered. */ - vss_transaction.active = true; + vss_transaction.state = HVUTIL_DEVICE_INIT; + return 0; } void hv_vss_deinit(void) { + vss_transaction.state = HVUTIL_DEVICE_DYING; cn_del_callback(&vss_id); cancel_delayed_work_sync(&vss_timeout_work); cancel_work_sync(&vss_send_op_work); |