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-rw-r--r--drivers/hv/hv_snapshot.c87
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);