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authorCássio Gabriel <cassiogabrielcontato@gmail.com>2026-05-26 09:48:27 -0300
committerTakashi Iwai <tiwai@suse.de>2026-05-27 07:25:53 +0200
commit3624f0bd4af15a820b1bd88b489980fa9fd61b7a (patch)
tree8abf492011b96f007324270d6898659767098b71 /sound
parent9cd81152373c560b8aa8299b0705c4db82b103b7 (diff)
downloadlinux-next-history-3624f0bd4af15a820b1bd88b489980fa9fd61b7a.tar.gz
ALSA: xen-front: Connect event channel after stream prepare
The request channel must be connected from ALSA .open(), because hw-rule queries and the stream open request use it. The event channel is different: XENSND_EVT_CUR_POS handling uses ALSA runtime buffer and period geometry, and the corresponding Xen stream parameters are not submitted to the backend until .prepare() sends XENSND_OP_OPEN. Currently .open() connects both channels. A backend current-position event, or a stale event queued for an earlier stream instance, can therefore reach xen_snd_front_alsa_handle_cur_pos() before runtime->buffer_size and runtime->period_size are valid. Add a per-channel connection helper, connect only the request channel in .open(), connect the event channel after a successful stream prepare, and disconnect it before stream close/free. Re-check the event-channel state after taking ring_io_lock so disconnecting the event channel synchronizes against a threaded IRQ that passed the initial lockless state test. Keep defensive runtime geometry checks in the position handler. Fixes: 1cee559351a7 ("ALSA: xen-front: Implement ALSA virtual sound driver") Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com> Link: https://patch.msgid.link/20260526-alsa-xen-event-channel-fixes-v1-2-91d3a6a50778@gmail.com Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound')
-rw-r--r--sound/xen/xen_snd_front_alsa.c17
-rw-r--r--sound/xen/xen_snd_front_evtchnl.c20
-rw-r--r--sound/xen/xen_snd_front_evtchnl.h2
3 files changed, 27 insertions, 12 deletions
diff --git a/sound/xen/xen_snd_front_alsa.c b/sound/xen/xen_snd_front_alsa.c
index dc626480123ac..a6dd196f73d66 100644
--- a/sound/xen/xen_snd_front_alsa.c
+++ b/sound/xen/xen_snd_front_alsa.c
@@ -378,7 +378,7 @@ static int alsa_open(struct snd_pcm_substream *substream)
stream_clear(stream);
- xen_snd_front_evtchnl_pair_set_connected(stream->evt_pair, true);
+ xen_snd_front_evtchnl_set_connected(&stream->evt_pair->req, true);
ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_FORMAT,
alsa_hw_rule, stream,
@@ -498,6 +498,8 @@ static int alsa_hw_free(struct snd_pcm_substream *substream)
struct xen_snd_front_pcm_stream_info *stream = stream_get(substream);
int ret;
+ xen_snd_front_evtchnl_set_connected(&stream->evt_pair->evt, false);
+
ret = xen_snd_front_stream_close(&stream->evt_pair->req);
stream_free(stream);
return ret;
@@ -532,6 +534,7 @@ static int alsa_prepare(struct snd_pcm_substream *substream)
return ret;
stream->is_open = true;
+ xen_snd_front_evtchnl_set_connected(&stream->evt_pair->evt, true);
}
return 0;
@@ -571,20 +574,24 @@ void xen_snd_front_alsa_handle_cur_pos(struct xen_snd_front_evtchnl *evtchnl,
{
struct snd_pcm_substream *substream = evtchnl->u.evt.substream;
struct xen_snd_front_pcm_stream_info *stream = stream_get(substream);
+ struct snd_pcm_runtime *runtime = substream->runtime;
snd_pcm_uframes_t delta, new_hw_ptr, cur_frame;
- cur_frame = bytes_to_frames(substream->runtime, pos_bytes);
+ if (!runtime->buffer_size || !runtime->period_size)
+ return;
+
+ cur_frame = bytes_to_frames(runtime, pos_bytes);
delta = cur_frame - stream->be_cur_frame;
stream->be_cur_frame = cur_frame;
new_hw_ptr = (snd_pcm_uframes_t)atomic_read(&stream->hw_ptr);
- new_hw_ptr = (new_hw_ptr + delta) % substream->runtime->buffer_size;
+ new_hw_ptr = (new_hw_ptr + delta) % runtime->buffer_size;
atomic_set(&stream->hw_ptr, (int)new_hw_ptr);
stream->out_frames += delta;
- if (stream->out_frames > substream->runtime->period_size) {
- stream->out_frames %= substream->runtime->period_size;
+ if (stream->out_frames > runtime->period_size) {
+ stream->out_frames %= runtime->period_size;
snd_pcm_period_elapsed(substream);
}
}
diff --git a/sound/xen/xen_snd_front_evtchnl.c b/sound/xen/xen_snd_front_evtchnl.c
index 09e4c1d056363..17a30452c0cca 100644
--- a/sound/xen/xen_snd_front_evtchnl.c
+++ b/sound/xen/xen_snd_front_evtchnl.c
@@ -94,6 +94,9 @@ static irqreturn_t evtchnl_interrupt_evt(int irq, void *dev_id)
guard(mutex)(&channel->ring_io_lock);
+ if (unlikely(channel->state != EVTCHNL_STATE_CONNECTED))
+ return IRQ_HANDLED;
+
prod = page->in_prod;
/* Ensure we see ring contents up to prod. */
virt_rmb();
@@ -430,8 +433,8 @@ fail_to_end:
return ret;
}
-void xen_snd_front_evtchnl_pair_set_connected(struct xen_snd_front_evtchnl_pair *evt_pair,
- bool is_connected)
+void xen_snd_front_evtchnl_set_connected(struct xen_snd_front_evtchnl *channel,
+ bool is_connected)
{
enum xen_snd_front_evtchnl_state state;
@@ -440,13 +443,16 @@ void xen_snd_front_evtchnl_pair_set_connected(struct xen_snd_front_evtchnl_pair
else
state = EVTCHNL_STATE_DISCONNECTED;
- scoped_guard(mutex, &evt_pair->req.ring_io_lock) {
- evt_pair->req.state = state;
+ scoped_guard(mutex, &channel->ring_io_lock) {
+ channel->state = state;
}
+}
- scoped_guard(mutex, &evt_pair->evt.ring_io_lock) {
- evt_pair->evt.state = state;
- }
+void xen_snd_front_evtchnl_pair_set_connected(struct xen_snd_front_evtchnl_pair *evt_pair,
+ bool is_connected)
+{
+ xen_snd_front_evtchnl_set_connected(&evt_pair->req, is_connected);
+ xen_snd_front_evtchnl_set_connected(&evt_pair->evt, is_connected);
}
void xen_snd_front_evtchnl_pair_clear(struct xen_snd_front_evtchnl_pair *evt_pair)
diff --git a/sound/xen/xen_snd_front_evtchnl.h b/sound/xen/xen_snd_front_evtchnl.h
index 8400261ac4660..f6ebdb09c0298 100644
--- a/sound/xen/xen_snd_front_evtchnl.h
+++ b/sound/xen/xen_snd_front_evtchnl.h
@@ -77,6 +77,8 @@ void xen_snd_front_evtchnl_free_all(struct xen_snd_front_info *front_info);
int xen_snd_front_evtchnl_publish_all(struct xen_snd_front_info *front_info);
void xen_snd_front_evtchnl_flush(struct xen_snd_front_evtchnl *evtchnl);
+void xen_snd_front_evtchnl_set_connected(struct xen_snd_front_evtchnl *channel,
+ bool is_connected);
void xen_snd_front_evtchnl_pair_set_connected(struct xen_snd_front_evtchnl_pair *evt_pair,
bool is_connected);
generated by cgit 1.3-korg (git 2.53.0) at 2026-06-01 05:02:52 +0000