Race condition when executing lldpcli in parallel #343
Description
Executing
lldpcli -ddddd configure system hostname foolldpcli -ddddd configure system description bar
in parallel may results in:
- hostname:
(none)(fooexpected) - description:
bar
$ lldpcli configure system hostname foo & lldpcli configure system description bar
$ lldpcli show configuration
-------------------------------------------------------------------------------
Global configuration:
-------------------------------------------------------------------------------
Configuration:
Transmit delay: 30
...
Override description with: bar
^^^ OK
Override platform with: Darwin
Override system name with: (none)
^^^^^^ expected foo
Advertise version: yes
...
-------------------------------------------------------------------------------Here's a sequence diagram (generated with PlantUML) explaining what happened:
To reproduce this easily, I patched the following diff:
diff --git a/src/daemon/event.c b/src/daemon/event.c
index c42bc3fa..998807b9 100644
--- a/src/daemon/event.c
+++ b/src/daemon/event.c
@@ -330,6 +330,8 @@ levent_ctl_recv(struct bufferevent *bev, void *ptr)
void *data = NULL;
log_debug("control", "receive data on Unix socket");
+ log_debug("control", "sleep(5)");
+ sleep(5);
if (buffer_len < sizeof(struct hmsg_header))
return; /* Not enough data yet */
if (evbuffer_copyout(buffer, &hdr,Log from lldpd -ddddd:
$ lldpd -ddddd
$ lldpcli configure system hostname foo
handle GET_CONFIG from lldpcli 1 (hostname foo)
2019-09-04T13:09:31 [ DBG/control] accept a new connection
2019-09-04T13:09:31 [ DBG/event] new client accepted
2019-09-04T13:09:31 [ DBG/control] receive data on Unix socket
2019-09-04T13:09:31 [ DBG/control] sleep(5)
$ lldpcli configure system description bar
2019-09-04T13:09:36 [ DBG/rpc] handle client request
2019-09-04T13:09:36 [ DBG/rpc] client requested configuration
2019-09-04T13:09:36 [ DBG/marshal] start serialization of lldpd_config
2019-09-04T13:09:36 [ DBG/marshal] start serialization of null string
handle GET_CONFIG from lldpcli 2 (description bar)
2019-09-04T13:09:36 [ DBG/control] accept a new connection
2019-09-04T13:09:36 [ DBG/event] new client accepted
2019-09-04T13:09:36 [ DBG/control] receive data on Unix socket
2019-09-04T13:09:36 [ DBG/control] sleep(5)
2019-09-04T13:09:41 [ DBG/rpc] handle client request
2019-09-04T13:09:41 [ DBG/rpc] client requested configuration
2019-09-04T13:09:41 [ DBG/marshal] start serialization of lldpd_config
2019-09-04T13:09:41 [ DBG/marshal] start serialization of null string
handle SET_CONFIG from lldpcli 1 (hostname foo)
2019-09-04T13:09:41 [ DBG/control] receive data on Unix socket
2019-09-04T13:09:41 [ DBG/control] sleep(5)
2019-09-04T13:09:46 [ DBG/rpc] handle client request
2019-09-04T13:09:46 [ DBG/rpc] client request a change in configuration
2019-09-04T13:09:46 [ DBG/marshal] start unserialization of lldpd_config
2019-09-04T13:09:46 [ DBG/marshal] start unserialization of null string
2019-09-04T13:09:46 [ DBG/marshal] start unserialization of null string
2019-09-04T13:09:46 [ DBG/rpc] change system name to foo
2019-09-04T13:09:46 [ DBG/localchassis] update information for local chassis
2019-09-04T13:09:46 [ DBG/localchassis] use overridden system name `foo`
2019-09-04T13:09:46 [ DBG/localchassis] advertise system version
2019-09-04T13:09:46 [ DBG/alloc] general configuration cleanup
2019-09-04T13:09:46 [ DBG/loop] start new loop
2019-09-04T13:09:46 [ DBG/loop] update information for local ports
2019-09-04T13:09:46 [ DBG/localchassis] update information for local ports
2019-09-04T13:09:46 [ DBG/interfaces] grabbing information on interface lo0
...
2019-09-04T13:09:46 [ DBG/localchassis] update information for local chassis
2019-09-04T13:09:46 [ DBG/localchassis] use overridden system name `foo`
2019-09-04T13:09:46 [ DBG/localchassis] advertise system version
handle SET_CONFIG from lldpcli 2 (description bar)
2019-09-04T13:09:46 [ DBG/control] receive data on Unix socket
2019-09-04T13:09:46 [ DBG/control] sleep(5)
2019-09-04T13:09:51 [ DBG/rpc] handle client request
2019-09-04T13:09:51 [ DBG/rpc] client request a change in configuration
2019-09-04T13:09:51 [ DBG/marshal] start unserialization of lldpd_config
2019-09-04T13:09:51 [ DBG/marshal] start unserialization of null string
2019-09-04T13:09:51 [ DBG/marshal] start unserialization of null string
2019-09-04T13:09:51 [ DBG/rpc] change chassis description to bar
2019-09-04T13:09:51 [ DBG/localchassis] update information for local chassis
2019-09-04T13:09:51 [ DBG/localchassis] use overridden system name `foo`
2019-09-04T13:09:51 [ DBG/localchassis] use overridden description `bar`
2019-09-04T13:09:51 [ DBG/rpc] change system name to (NULL)
2019-09-04T13:09:51 [ DBG/localchassis] update information for local chassis
2019-09-04T13:09:51 [ DBG/privsep] received command 2
2019-09-04T13:09:51 [ DBG/localchassis] use overridden description `bar`
2019-09-04T13:09:51 [ DBG/alloc] general configuration cleanup
2019-09-04T13:09:51 [ DBG/loop] start new loop
2019-09-04T13:09:51 [ DBG/loop] update information for local ports
2019-09-04T13:09:51 [ DBG/localchassis] update information for local ports
...
2019-09-04T13:09:51 [ DBG/localchassis] update information for local chassis
2019-09-04T13:09:51 [ DBG/privsep] received command 2
2019-09-04T13:09:51 [ DBG/localchassis] use overridden description `bar`
2019-09-04T13:09:51 [ DBG/event] client has been disconnected
2019-09-04T13:09:51 [ DBG/event] trigger sending PDU for port en0
2019-09-04T13:09:51 [ DBG/send] send PDU on en0
2019-09-04T13:09:51 [ DBG/send] fallback to protocol LLDP for en0
2019-09-04T13:09:51 [ DBG/lldp] send LLDP PDU to en0
2019-09-04T13:09:51 [ DBG/interfaces] send PDU to ethernet device en0 (fd=8)
2019-09-04T13:09:51 [ DBG/event] trigger sending PDU for port en1
2019-09-04T13:09:51 [ DBG/event] client has been disconnected