From fc23037a9aaf0beca99f9494948b2fb1169a03db Mon Sep 17 00:00:00 2001 From: Antoine Tremblay Date: Tue, 10 Feb 2009 11:00:12 +0100 Subject: [PATCH] alsamixer: Fix race condition that made alsamixer not working properly This is due to race conditions between functions that modified the mixer like set_volume and snd_mixer_handle_events since the handle_events can now be called at any time. Fixed by adding locking around any snd_mixer call since even read functions can modify the mixer stucture, since alsa likes to clear it's values before reading new ones. The favorite race condition seemed to be that set_volume called read_elem (in alsalib) that reset the volumes to 0 and then read them with read_x_volume. This read looped on each channel and as the race condition occured the channels value could be anything , most of the time it was 0. Thus no value was read or only the value of one channel was and the volume was reset to 0. Fixes bug #478512. --- ext/alsa/gstalsamixer.c | 37 ++++++++++++++++++++++++++++++++----- 1 file changed, 32 insertions(+), 5 deletions(-) diff --git a/ext/alsa/gstalsamixer.c b/ext/alsa/gstalsamixer.c index cefbd0c..fc6497c 100644 --- a/ext/alsa/gstalsamixer.c +++ b/ext/alsa/gstalsamixer.c @@ -129,11 +129,14 @@ gst_alsa_mixer_find_master_mixer (GstAlsaMixer * mixer, snd_mixer_t * handle) count = snd_mixer_get_count (handle); + g_static_rec_mutex_lock (mixer->rec_mutex); + /* Check if we have a playback mixer labelled as 'Master' */ element = snd_mixer_first_elem (handle); for (i = 0; i < count; i++) { if (snd_mixer_selem_has_playback_volume (element) && strcmp (snd_mixer_selem_get_name (element), "Master") == 0) { + g_static_rec_mutex_unlock (mixer->rec_mutex); return element; } element = snd_mixer_elem_next (element); @@ -144,6 +147,7 @@ gst_alsa_mixer_find_master_mixer (GstAlsaMixer * mixer, snd_mixer_t * handle) for (i = 0; i < count; i++) { if (snd_mixer_selem_has_playback_volume (element) && strcmp (snd_mixer_selem_get_name (element), "Front") == 0) { + g_static_rec_mutex_unlock (mixer->rec_mutex); return element; } element = snd_mixer_elem_next (element); @@ -154,6 +158,7 @@ gst_alsa_mixer_find_master_mixer (GstAlsaMixer * mixer, snd_mixer_t * handle) for (i = 0; i < count; i++) { if (snd_mixer_selem_has_playback_volume (element) && strcmp (snd_mixer_selem_get_name (element), "PCM") == 0) { + g_static_rec_mutex_unlock (mixer->rec_mutex); return element; } element = snd_mixer_elem_next (element); @@ -186,6 +191,7 @@ gst_alsa_mixer_find_master_mixer (GstAlsaMixer * mixer, snd_mixer_t * handle) for (i = 0; i < count; i++) { if (snd_mixer_selem_has_playback_volume (element) && snd_mixer_selem_has_playback_switch (element)) { + g_static_rec_mutex_unlock (mixer->rec_mutex); return element; } element = snd_mixer_elem_next (element); @@ -195,11 +201,13 @@ gst_alsa_mixer_find_master_mixer (GstAlsaMixer * mixer, snd_mixer_t * handle) element = snd_mixer_first_elem (handle); for (i = 0; i < count; i++) { if (snd_mixer_selem_has_playback_volume (element)) { + g_static_rec_mutex_unlock (mixer->rec_mutex); return element; } element = snd_mixer_elem_next (element); } + g_static_rec_mutex_unlock (mixer->rec_mutex); /* Looks like we're out of luck ... */ return NULL; } @@ -571,6 +579,8 @@ gst_alsa_mixer_get_volume (GstAlsaMixer * mixer, GstMixerTrack * track, g_return_if_fail (mixer->handle != NULL); + g_static_rec_mutex_lock (mixer->rec_mutex); + gst_alsa_mixer_track_update (alsa_track); if (track->flags & GST_MIXER_TRACK_OUTPUT) { /* return playback volume */ @@ -605,6 +615,7 @@ gst_alsa_mixer_get_volume (GstAlsaMixer * mixer, GstMixerTrack * track, volumes[i] = alsa_track->volumes[i]; } } + g_static_rec_mutex_unlock (mixer->rec_mutex); } static gboolean @@ -632,6 +643,8 @@ gst_alsa_mixer_set_volume (GstAlsaMixer * mixer, GstMixerTrack * track, g_return_if_fail (mixer->handle != NULL); + g_static_rec_mutex_lock (mixer->rec_mutex); + gst_alsa_mixer_track_update (alsa_track); if (track->flags & GST_MIXER_TRACK_OUTPUT) { @@ -678,6 +691,7 @@ gst_alsa_mixer_set_volume (GstAlsaMixer * mixer, GstMixerTrack * track, alsa_track->volumes[i] = volumes[i]; } } + g_static_rec_mutex_unlock (mixer->rec_mutex); } void @@ -688,11 +702,14 @@ gst_alsa_mixer_set_mute (GstAlsaMixer * mixer, GstMixerTrack * track, g_return_if_fail (mixer->handle != NULL); + g_static_rec_mutex_lock (mixer->rec_mutex); + gst_alsa_mixer_track_update (alsa_track); - if (!!(mute) == !!(track->flags & GST_MIXER_TRACK_MUTE)) + if (!!(mute) == !!(track->flags & GST_MIXER_TRACK_MUTE)) { + g_static_rec_mutex_unlock (mixer->rec_mutex); return; - + } if (mute) { track->flags |= GST_MIXER_TRACK_MUTE; @@ -726,6 +743,7 @@ gst_alsa_mixer_set_mute (GstAlsaMixer * mixer, GstMixerTrack * track, snd_mixer_selem_set_playback_volume (ctrl_track->element, i, vol); } } + g_static_rec_mutex_unlock (mixer->rec_mutex); } void @@ -736,10 +754,14 @@ gst_alsa_mixer_set_record (GstAlsaMixer * mixer, g_return_if_fail (mixer->handle != NULL); + g_static_rec_mutex_lock (mixer->rec_mutex); + gst_alsa_mixer_track_update (alsa_track); - if (!!(record) == !!(track->flags & GST_MIXER_TRACK_RECORD)) + if (!!(record) == !!(track->flags & GST_MIXER_TRACK_RECORD)) { + g_static_rec_mutex_unlock (mixer->rec_mutex); return; + } if (record) { track->flags |= GST_MIXER_TRACK_RECORD; @@ -777,6 +799,7 @@ gst_alsa_mixer_set_record (GstAlsaMixer * mixer, snd_mixer_selem_set_capture_volume (alsa_track->element, i, vol); } } + g_static_rec_mutex_unlock (mixer->rec_mutex); } void @@ -798,7 +821,9 @@ gst_alsa_mixer_set_option (GstAlsaMixer * mixer, if (idx == -1) return; + g_static_rec_mutex_lock (mixer->rec_mutex); snd_mixer_selem_set_enum_item (alsa_opts->element, 0, idx); + g_static_rec_mutex_unlock (mixer->rec_mutex); } const gchar * @@ -809,8 +834,9 @@ gst_alsa_mixer_get_option (GstAlsaMixer * mixer, GstMixerOptions * opts) GstAlsaMixerOptions *alsa_opts = GST_ALSA_MIXER_OPTIONS (opts); g_return_val_if_fail (mixer->handle != NULL, NULL); - + g_static_rec_mutex_lock (mixer->rec_mutex); ret = snd_mixer_selem_get_enum_item (alsa_opts->element, 0, &idx); + g_static_rec_mutex_unlock (mixer->rec_mutex); if (ret == 0) return g_list_nth_data (opts->values, idx); else @@ -837,8 +863,9 @@ gst_alsa_mixer_update_option (GstAlsaMixer * mixer, GST_WARNING ("Cannot send update notifications, no GstMixer * given"); return; } - + g_static_rec_mutex_lock (mixer->rec_mutex); ret = snd_mixer_selem_get_enum_item (alsa_opts->element, 0, &idx); + g_static_rec_mutex_unlock (mixer->rec_mutex); if (ret == 0) { option = g_list_nth_data (GST_MIXER_OPTIONS (alsa_opts)->values, idx); gst_mixer_option_changed (mixer->interface, GST_MIXER_OPTIONS (alsa_opts), -- 2.7.4