[PATCH] qv4l2: Prevent high CPU usage on device disconnect

[Tasos Sahanidis]

On device disconnect, ApplicationWindow::ctrlEvent() gets called
continuously, causing high CPU usage.
Closing the device handles once ENODEV is returned fixes this.
---
 utils/qv4l2/alsa_stream.c |  2 +-
 utils/qv4l2/qv4l2.cpp     | 24 +++++++++++++++++++-----
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/utils/qv4l2/alsa_stream.c b/utils/qv4l2/alsa_stream.c
index 05944822..2dca283b 100644
--- a/utils/qv4l2/alsa_stream.c
+++ b/utils/qv4l2/alsa_stream.c
@@ -433,7 +433,7 @@ static snd_pcm_sframes_t readbuf(snd_pcm_t *handle, char 
*buf, long len)
     snd_pcm_uframes_t frames;
     snd_pcm_htimestamp(handle, &frames, &timestamp);
     r = snd_pcm_readi(handle, buf, len);
-    if (r < 0 && r != -EAGAIN) {
+    if (r < 0 && !(r == -EAGAIN || r == -ENODEV)) {
        r = snd_pcm_recover(handle, r, 0);
        if (r < 0)
            fprintf(error_fp, "alsa: overrun recover error: %s\n", 
snd_strerror(r));
diff --git a/utils/qv4l2/qv4l2.cpp b/utils/qv4l2/qv4l2.cpp
index b52a3b60..9ac2c332 100644
--- a/utils/qv4l2/qv4l2.cpp
+++ b/utils/qv4l2/qv4l2.cpp
@@ -495,8 +495,9 @@ void ApplicationWindow::setAudioBufferSize()
 void ApplicationWindow::ctrlEvent()
 {
        v4l2_event ev;
+       int event_ret = 0;
 
-       while (dqevent(ev) == 0) {
+       while ((event_ret = dqevent(ev)) == 0) {
                if (ev.type == V4L2_EVENT_SOURCE_CHANGE) {
                        m_genTab->sourceChange(ev);
                        continue;
@@ -551,6 +552,15 @@ void ApplicationWindow::ctrlEvent()
                        setString(ev.id, c.string);
                free(c.string);
        }
+
+       if (event_ret && errno == ENODEV) {
+               closeDevice();
+               if (m_capture != NULL) {
+                       m_capture->stop();
+                       delete m_capture;
+                       m_capture = NULL;
+               }
+       }
 }
 
 void ApplicationWindow::newCaptureWin()
@@ -558,6 +568,7 @@ void ApplicationWindow::newCaptureWin()
        if (m_capture != NULL) {
                m_capture->stop();
                delete m_capture;
+               m_capture = NULL;
        }
 
        switch (m_renderMethod) {
@@ -1135,7 +1146,7 @@ void ApplicationWindow::stopStreaming()
        if (!m_genTab->isSDR() && m_genTab->isRadio())
                return;
 
-       if (v4l_type_is_capture(g_type()))
+       if (v4l_type_is_capture(g_type()) && m_capture != NULL)
                m_capture->stop();
 
        m_snapshotAct->setDisabled(true);
@@ -1561,8 +1572,10 @@ void ApplicationWindow::makeFullScreen(bool checked)
 void ApplicationWindow::closeDevice()
 {
        stopAudio();
-       delete m_sigMapper;
-       m_sigMapper = NULL;
+       if(m_sigMapper != NULL) {
+               m_sigMapper->deleteLater();
+               m_sigMapper = NULL;
+       }
        m_capStartAct->setEnabled(false);
        m_capStartAct->setChecked(false);
        m_capStepAct->setEnabled(false);
@@ -1579,7 +1592,7 @@ void ApplicationWindow::closeDevice()
                        m_outNotifier = NULL;
                }
                if (m_ctrlNotifier) {
-                       delete m_ctrlNotifier;
+                       m_ctrlNotifier->deleteLater();
                        m_ctrlNotifier = NULL;
                }
                delete [] m_frameData;
@@ -1740,6 +1753,7 @@ void ApplicationWindow::closeEvent(QCloseEvent *event)
 {
        closeDevice();
        delete m_capture;
+       m_capture = NULL;
        event->accept();
 }
 
-- 
2.20.1