When a new DisplayChannelClient is connected, we send out a monitors
config message so that the client knows the current state of the display
configuration. In some circumstances (e.g. virt-viewer fullscreen
auto-conf), the client will send a monitors config message as soon as
the vdagent is connected. This can happen before the display channel
client is connected. So we can get into a situation where the
DisplayChannelClient is sending out a stale monitors configuration
message while the guest is in the process of re-configuring its
displays. This can cause misbehavior on the guest. To avoid this race,
we keep track of whether we have received a MonitorsConfig message from
the client prior to sending out our initial MonitorsConfig message from
the server. If so, we delay our initial message to give the server a
chance to handle the re-configuration requested by the client.
---
server/main_channel.c | 13 +++++++++++++
server/main_channel.h | 3 +++
server/red_worker.c | 38 ++++++++++++++++++++++++++++++++++++--
server/reds.c | 1 +
4 files changed, 53 insertions(+), 2 deletions(-)
diff --git a/server/main_channel.c b/server/main_channel.c
index 54718ba..111e139 100644
--- a/server/main_channel.c
+++ b/server/main_channel.c
@@ -160,6 +160,7 @@ struct MainChannelClient {
int mig_wait_prev_try_seamless;
int init_sent;
int seamless_mig_dst;
+ int monitors_config_recvd;
};
enum NetTestStage {
@@ -1112,6 +1113,7 @@ static MainChannelClient *main_channel_client_create(MainChannel *main_chan, Red
spice_assert(mcc != NULL);
mcc->connection_id = connection_id;
mcc->bitrate_per_sec = ~0;
+ mcc->monitors_config_recvd = FALSE;
#ifdef RED_STATISTICS
if (!(mcc->ping_timer = core->timer_add(ping_timer_cb, NULL))) {
spice_error("ping timer create failed");
@@ -1364,3 +1366,14 @@ int main_channel_migrate_src_complete(MainChannel *main_chan, int success)
}
return semi_seamless_count;
}
+
+void main_channel_client_received_monitors_config(MainChannelClient *mcc)
+{
+ mcc->monitors_config_recvd = TRUE;
+}
+
+int main_channel_client_did_receive_monitors_config(MainChannelClient *mcc)
+{
+ return mcc->monitors_config_recvd;
+}
+
diff --git a/server/main_channel.h b/server/main_channel.h
index c8e9ade..267bcc1 100644
--- a/server/main_channel.h
+++ b/server/main_channel.h
@@ -95,4 +95,7 @@ void main_channel_migrate_dst_complete(MainChannelClient *mcc);
void main_channel_push_name(MainChannelClient *mcc, const char *name);
void main_channel_push_uuid(MainChannelClient *mcc, const uint8_t uuid[16]);
+void main_channel_client_received_monitors_config(MainChannelClient *mcc);
+int main_channel_client_did_receive_monitors_config(MainChannelClient *mcc);
+
#endif
diff --git a/server/red_worker.c b/server/red_worker.c
index 5deb30b..dfe8e04 100644
--- a/server/red_worker.c
+++ b/server/red_worker.c
@@ -726,6 +726,7 @@ struct DisplayChannelClient {
int use_mjpeg_encoder_rate_control;
uint32_t streams_max_latency;
uint64_t streams_max_bit_rate;
+ SpiceTimer *monitors_config_timer;
};
struct DisplayChannel {
@@ -9831,11 +9832,24 @@ static int display_channel_client_wait_for_init(DisplayChannelClient *dcc)
return FALSE;
}
+static void red_push_monitors_config_internal(DisplayChannelClient *dcc);
+static void red_schedule_push_monitors_config(DisplayChannelClient *dcc)
+{
+ spice_debug("Scheduling push_monitors_config for later to avoid race...");
+ if (!dcc->monitors_config_timer)
+ dcc->monitors_config_timer = spice_timer_queue_add((SpiceTimerFunc)red_push_monitors_config_internal, dcc);
+
+ spice_assert(dcc->monitors_config_timer);
+ spice_timer_set(dcc->monitors_config_timer, 1000);
+}
+
static void on_new_display_channel_client(DisplayChannelClient *dcc)
{
DisplayChannel *display_channel = DCC_TO_DC(dcc);
RedWorker *worker = display_channel->common.worker;
RedChannelClient *rcc = &dcc->common.base;
+ RedClient *client = red_channel_client_get_client(rcc);
+ MainChannelClient *mcc = red_client_get_main(client);
red_channel_client_push_set_ack(&dcc->common.base);
@@ -9851,7 +9865,16 @@ static void on_new_display_channel_client(DisplayChannelClient *dcc)
red_current_flush(worker, 0);
push_new_primary_surface(dcc);
red_push_surface_image(dcc, 0);
- red_push_monitors_config(dcc);
+ if(main_channel_client_did_receive_monitors_config(mcc)) {
+ /* if we received a monitors config message from the client before
+ * we could send out a monitors config message from the server,
+ * there is a potential for a race where we send a stale monitors
+ * configuration to the client. Schedule this message for later to
+ * avoid this race*/
+ red_schedule_push_monitors_config(dcc);
+ } else {
+ red_push_monitors_config(dcc);
+ }
red_pipe_add_verb(rcc, SPICE_MSG_DISPLAY_MARK);
red_disply_start_streams(dcc);
}
@@ -10464,6 +10487,7 @@ DisplayChannelClient *display_channel_client_create(CommonChannel *common,
}
ring_init(&dcc->palette_cache_lru);
dcc->palette_cache_available = CLIENT_PALETTE_CACHE_SIZE;
+ dcc->monitors_config_timer = NULL;
return dcc;
}
@@ -11262,7 +11286,8 @@ static void worker_update_monitors_config(RedWorker *worker,
memcpy(monitors_config->heads, dev_monitors_config->heads, heads_size);
}
-static void red_push_monitors_config(DisplayChannelClient *dcc)
+/* don't remove the timer */
+static void red_push_monitors_config_internal(DisplayChannelClient *dcc)
{
MonitorsConfig *monitors_config = DCC_TO_WORKER(dcc)->monitors_config;
@@ -11279,6 +11304,15 @@ static void red_push_monitors_config(DisplayChannelClient *dcc)
red_channel_client_push(&dcc->common.base);
}
+static void red_push_monitors_config(DisplayChannelClient *dcc)
+{
+ if (dcc->monitors_config_timer) {
+ spice_timer_remove(dcc->monitors_config_timer);
+ dcc->monitors_config_timer = NULL;
+ }
+ red_push_monitors_config_internal(dcc);
+}
+
static void red_worker_push_monitors_config(RedWorker *worker)
{
DisplayChannelClient *dcc;
diff --git a/server/reds.c b/server/reds.c
index 4e36961..206702d 100644
--- a/server/reds.c
+++ b/server/reds.c
@@ -1033,6 +1033,7 @@ void reds_on_main_agent_data(MainChannelClient *mcc, void *message, size_t size)
case AGENT_MSG_FILTER_DISCARD:
return;
case AGENT_MSG_FILTER_MONITORS_CONFIG:
+ main_channel_client_received_monitors_config(mcc);
if (red_dispatcher_use_client_monitors_config()) {
reds_on_main_agent_monitors_config(mcc, message, size);
return;
--
2.1.0
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