解决：QWSLock::up(): down(): Invalid argument

这是Qt4.8.6自带的bug。

对qwslock的文件进行下面的修改：

diff --git a/src/gui/embedded/qwslock.cpp b/src/gui/embedded/qwslock.cpp
index 9914a24..1055785 100644
--- a/src/gui/embedded/qwslock.cpp
+++ b/src/gui/embedded/qwslock.cpp
@@ -83,9 +83,12 @@ QWSLock::QWSLock(int id) : semId(id)
     QWSSignalHandler::instance()->addWSLock(this);
 #endif
 
+    owned = false;
+
 #ifndef QT_POSIX_IPC
     if (semId == -1) {
         semId = semget(IPC_PRIVATE, 3, IPC_CREAT | 0666);
+        owned = true;
         if (semId == -1) {
             perror("QWSLock::QWSLock");
             qFatal("Unable to create semaphore");
@@ -100,7 +104,6 @@ QWSLock::QWSLock(int id) : semId(id)
     }
 #else
     sems[0] = sems[1] = sems[2] = SEM_FAILED;
-    owned = false;
 
     if (semId == -1) {
         // ### generate really unique IDs
@@ -134,9 +137,11 @@ QWSLock::~QWSLock()
 
     if (semId != -1) {
 #ifndef QT_POSIX_IPC
-        qt_semun semval;
-        semval.val = 0;
-        semctl(semId, 0, IPC_RMID, semval);
+   if (owned) {
+       qt_semun semval;
+       semval.val = 0;
+       semctl(semId, 0, IPC_RMID, semval);
+   }
         semId = -1;
 #else
         // emulate the SEM_UNDO behavior for the BackingStore lock
diff --git a/src/gui/embedded/qwslock_p.h b/src/gui/embedded/qwslock_p.h
index d324e4f..d867d20 100644
--- a/src/gui/embedded/qwslock_p.h
+++ b/src/gui/embedded/qwslock_p.h
@@ -86,8 +86,8 @@ private:
     int lockCount[2];
 #ifdef QT_POSIX_IPC
     sem_t *sems[3];
-    bool owned;
 #endif
+    bool owned;
 };
 
 QT_END_NAMESPACE

重新编译以后，将对应的lib拷贝到arm板上面。重启板子以后，运行程序，发现这个不断的打印log就会消失了。

参考：

https://www.cnblogs.com/helloworldtoyou/p/6798034.html

https://git.congatec.com/yocto/poky/commit/d1b523e7dd55b11d1b02904a83a0464b95616c07