From cce89099c5c5fe722a191e1846b66f6adb42d02e Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Mon, 14 Feb 2022 17:28:16 +1100
Subject: [PATCH] GCS_MAVLink: fixed mavlink packet corruption with multiple
 threads

this ensures we don't try to send more data to a uart than is
available in the tx buffer
---
 libraries/GCS_MAVLink/GCS_Common.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libraries/GCS_MAVLink/GCS_Common.cpp b/libraries/GCS_MAVLink/GCS_Common.cpp
index b8a5284f5b..7c0e654823 100644
--- a/libraries/GCS_MAVLink/GCS_Common.cpp
+++ b/libraries/GCS_MAVLink/GCS_Common.cpp
@@ -2053,6 +2053,8 @@ void GCS_MAVLINK::service_statustext(void)
 {
     GCS::StatusTextQueue &_statustext_queue = gcs().statustext_queue();
 
+    WITH_SEMAPHORE(comm_chan_lock(chan));
+
     const uint8_t chan_bit = (1U<<chan);
     // note the lack of idx++ here.  We may remove the iteration item
     // from the queue as the last thing we do, in which case we don't