60 lines
2.5 KiB
Diff
60 lines
2.5 KiB
Diff
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From 4bdf4c99662f3da0e58d6c04bafff95d84362922 Mon Sep 17 00:00:00 2001
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From: Takashi Sakamoto <o-takashi@sakamocchi.jp>
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Date: Mon, 27 Jun 2022 10:09:52 +0900
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Subject: [PATCH] alsa-mixer: avoid assertion at alsa-lib mixer API when
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element removal
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PulseAudio v5.99 or later hits assertion at alsa-lib mixer API due to
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wrong handling of removal event for mixer element.
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pulseaudio: mixer.c:149: hctl_elem_event_handler: Assertion `bag_empty(bag)' failed.
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The removal event is defined as '~0U', thus it's not distinguished from
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the other type of event just by bitwise operator.
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At the removal event, class implementator for mixer API should detach
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mixer element from hcontrol element in callback handler since alsa-lib
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has assertion to check the list of mixer elements for a hcontrol element
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is empty or not after calling all of handlers. In detail, please refer to
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MR to alsa-lib:
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* https://github.com/alsa-project/alsa-lib/pull/244
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This commit fixes the above two issues. The issue can be regenerated by
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`samples/ctl` Python 3 script of alsa-gobject.
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* https://github.com/alsa-project/alsa-gobject/
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It adds some user-defined elements into sound card 0. When terminated by
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SIGINT signal, it removes the elements. Then PulseAudio dies due to the
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assertion.
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Fixes: 1fd8848e64cf ("alsa-util: Add functions for accessing mixer elements through mixer class")
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Part-of: <https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/728>
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---
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src/modules/alsa/alsa-util.c | 8 +++++++-
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1 file changed, 7 insertions(+), 1 deletion(-)
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diff --git a/src/modules/alsa/alsa-util.c b/src/modules/alsa/alsa-util.c
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index 7dc373fa0..f4e838d37 100644
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--- a/src/modules/alsa/alsa-util.c
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+++ b/src/modules/alsa/alsa-util.c
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@@ -1654,7 +1654,13 @@ static int mixer_class_event(snd_mixer_class_t *class, unsigned int mask,
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{
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int err;
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const char *name = snd_hctl_elem_get_name(helem);
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- if (mask & SND_CTL_EVENT_MASK_ADD) {
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+ /* NOTE: The remove event is defined as '~0U`. */
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+ if (mask == SND_CTL_EVENT_MASK_REMOVE) {
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+ /* NOTE: Unless we remove the pointer to melem from the linked-list at
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+ * private_data of helem, an assertion will be hit in alsa-lib since
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+ * the list is not empty. */
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+ snd_mixer_elem_detach(melem, helem);
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+ } else if (mask & SND_CTL_EVENT_MASK_ADD) {
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snd_ctl_elem_iface_t iface = snd_hctl_elem_get_interface(helem);
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if (iface == SND_CTL_ELEM_IFACE_CARD || iface == SND_CTL_ELEM_IFACE_PCM) {
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snd_mixer_elem_t *new_melem;
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--
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2.33.0
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