diff options
Diffstat (limited to 'src/modules/mavlink/mavlink_main.cpp')
| -rw-r--r-- | src/modules/mavlink/mavlink_main.cpp | 24 |
1 files changed, 22 insertions, 2 deletions
diff --git a/src/modules/mavlink/mavlink_main.cpp b/src/modules/mavlink/mavlink_main.cpp index 9c2e0178a..c9f4835ba 100644 --- a/src/modules/mavlink/mavlink_main.cpp +++ b/src/modules/mavlink/mavlink_main.cpp @@ -254,7 +254,6 @@ Mavlink::Mavlink() : break; } - LL_APPEND(_mavlink_instances, this); } Mavlink::~Mavlink() @@ -1778,6 +1777,9 @@ Mavlink::task_main(int argc, char *argv[]) /* set main loop delay depending on data rate to minimize CPU overhead */ _main_loop_delay = MAIN_LOOP_DELAY / rate_mult; + /* now the instance is fully initialized and we can bump the instance count */ + LL_APPEND(_mavlink_instances, this); + while (!_task_should_exit) { /* main loop */ usleep(_main_loop_delay); @@ -1924,10 +1926,18 @@ int Mavlink::start_helper(int argc, char *argv[]) int Mavlink::start(int argc, char *argv[]) { + // Wait for the instance count to go up one + // before returning to the shell + int ic = Mavlink::instance_count(); + // Instantiate thread char buf[24]; - sprintf(buf, "mavlink_if%d", Mavlink::instance_count()); + sprintf(buf, "mavlink_if%d", ic); + // This is where the control flow splits + // between the starting task and the spawned + // task - start_helper() only returns + // when the started task exits. task_spawn_cmd(buf, SCHED_DEFAULT, SCHED_PRIORITY_DEFAULT, @@ -1935,6 +1945,16 @@ Mavlink::start(int argc, char *argv[]) (main_t)&Mavlink::start_helper, (const char **)argv); + // Ensure that this shell command + // does not return before the instance + // is fully initialized. As this is also + // the only path to create a new instance, + // this is effectively a lock on concurrent + // instance starting. XXX do a real lock. + while (ic == Mavlink::instance_count()) { + ::usleep(500); + } + return OK; } |