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Re: [PATCH 01/10] hw/audio/virtio-sound: remove command and stream mutex
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From: |
Marc-André Lureau |
|
Subject: |
Re: [PATCH 01/10] hw/audio/virtio-sound: remove command and stream mutexes |
|
Date: |
Fri, 5 Jan 2024 14:10:02 +0400 |
Hi
On Fri, Jan 5, 2024 at 12:35 AM Volker Rümelin <vr_qemu@t-online.de> wrote:
>
> All code in virtio-snd.c runs with the BQL held. Remove the
> command queue mutex and the stream queue mutexes. The qatomic
> functions are also not needed.
I am not comfortable with this assertion. Someone more familiar with
virtio.c implementation should confirm
Rust would really save us from thinking about this kind of problems,
and a standalone vhost-user implementation..
>
> Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
> ---
> hw/audio/virtio-snd.c | 294 +++++++++++++++-------------------
> include/hw/audio/virtio-snd.h | 3 -
> 2 files changed, 130 insertions(+), 167 deletions(-)
>
> diff --git a/hw/audio/virtio-snd.c b/hw/audio/virtio-snd.c
> index ea2aeaef14..8344f61c64 100644
> --- a/hw/audio/virtio-snd.c
> +++ b/hw/audio/virtio-snd.c
> @@ -19,7 +19,6 @@
> #include "qemu/iov.h"
> #include "qemu/log.h"
> #include "qemu/error-report.h"
> -#include "include/qemu/lockable.h"
> #include "sysemu/runstate.h"
> #include "trace.h"
> #include "qapi/error.h"
> @@ -453,7 +452,6 @@ static uint32_t virtio_snd_pcm_prepare(VirtIOSound *s,
> uint32_t stream_id)
> stream->id = stream_id;
> stream->pcm = s->pcm;
> stream->s = s;
> - qemu_mutex_init(&stream->queue_mutex);
> QSIMPLEQ_INIT(&stream->queue);
> QSIMPLEQ_INIT(&stream->invalid);
>
> @@ -580,9 +578,7 @@ static void virtio_snd_handle_pcm_start_stop(VirtIOSound
> *s,
>
> stream = virtio_snd_pcm_get_stream(s, stream_id);
> if (stream) {
> - WITH_QEMU_LOCK_GUARD(&stream->queue_mutex) {
> - stream->active = start;
> - }
> + stream->active = start;
> if (stream->info.direction == VIRTIO_SND_D_OUTPUT) {
> AUD_set_active_out(stream->voice.out, start);
> } else {
> @@ -606,13 +602,11 @@ static size_t
> virtio_snd_pcm_get_io_msgs_count(VirtIOSoundPCMStream *stream)
> VirtIOSoundPCMBuffer *buffer, *next;
> size_t count = 0;
>
> - WITH_QEMU_LOCK_GUARD(&stream->queue_mutex) {
> - QSIMPLEQ_FOREACH_SAFE(buffer, &stream->queue, entry, next) {
> - count += 1;
> - }
> - QSIMPLEQ_FOREACH_SAFE(buffer, &stream->invalid, entry, next) {
> - count += 1;
> - }
> + QSIMPLEQ_FOREACH_SAFE(buffer, &stream->queue, entry, next) {
> + count += 1;
> + }
> + QSIMPLEQ_FOREACH_SAFE(buffer, &stream->invalid, entry, next) {
> + count += 1;
> }
> return count;
> }
> @@ -762,23 +756,15 @@ static void virtio_snd_process_cmdq(VirtIOSound *s)
> {
> virtio_snd_ctrl_command *cmd;
>
> - if (unlikely(qatomic_read(&s->processing_cmdq))) {
> - return;
> - }
> -
> - WITH_QEMU_LOCK_GUARD(&s->cmdq_mutex) {
> - qatomic_set(&s->processing_cmdq, true);
> - while (!QTAILQ_EMPTY(&s->cmdq)) {
> - cmd = QTAILQ_FIRST(&s->cmdq);
> + while (!QTAILQ_EMPTY(&s->cmdq)) {
> + cmd = QTAILQ_FIRST(&s->cmdq);
>
> - /* process command */
> - process_cmd(s, cmd);
> + /* process command */
> + process_cmd(s, cmd);
>
> - QTAILQ_REMOVE(&s->cmdq, cmd, next);
> + QTAILQ_REMOVE(&s->cmdq, cmd, next);
>
> - virtio_snd_ctrl_cmd_free(cmd);
> - }
> - qatomic_set(&s->processing_cmdq, false);
> + virtio_snd_ctrl_cmd_free(cmd);
> }
> }
>
> @@ -840,32 +826,30 @@ static inline void empty_invalid_queue(VirtIODevice
> *vdev, VirtQueue *vq)
> stream = vsnd->pcm->streams[i];
> if (stream) {
> any = false;
> - WITH_QEMU_LOCK_GUARD(&stream->queue_mutex) {
> - while (!QSIMPLEQ_EMPTY(&stream->invalid)) {
> - buffer = QSIMPLEQ_FIRST(&stream->invalid);
> - if (buffer->vq != vq) {
> - break;
> - }
> - any = true;
> - resp.status = cpu_to_le32(VIRTIO_SND_S_BAD_MSG);
> - iov_from_buf(buffer->elem->in_sg,
> - buffer->elem->in_num,
> - 0,
> - &resp,
> - sizeof(virtio_snd_pcm_status));
> - virtqueue_push(vq,
> - buffer->elem,
> - sizeof(virtio_snd_pcm_status));
> - QSIMPLEQ_REMOVE_HEAD(&stream->invalid, entry);
> - virtio_snd_pcm_buffer_free(buffer);
> - }
> - if (any) {
> - /*
> - * Notify vq about virtio_snd_pcm_status responses.
> - * Buffer responses must be notified separately later.
> - */
> - virtio_notify(vdev, vq);
> + while (!QSIMPLEQ_EMPTY(&stream->invalid)) {
> + buffer = QSIMPLEQ_FIRST(&stream->invalid);
> + if (buffer->vq != vq) {
> + break;
> }
> + any = true;
> + resp.status = cpu_to_le32(VIRTIO_SND_S_BAD_MSG);
> + iov_from_buf(buffer->elem->in_sg,
> + buffer->elem->in_num,
> + 0,
> + &resp,
> + sizeof(virtio_snd_pcm_status));
> + virtqueue_push(vq,
> + buffer->elem,
> + sizeof(virtio_snd_pcm_status));
> + QSIMPLEQ_REMOVE_HEAD(&stream->invalid, entry);
> + virtio_snd_pcm_buffer_free(buffer);
> + }
> + if (any) {
> + /*
> + * Notify vq about virtio_snd_pcm_status responses.
> + * Buffer responses must be notified separately later.
> + */
> + virtio_notify(vdev, vq);
> }
> }
> }
> @@ -924,28 +908,24 @@ static void virtio_snd_handle_tx_xfer(VirtIODevice
> *vdev, VirtQueue *vq)
> goto tx_err;
> }
>
> - WITH_QEMU_LOCK_GUARD(&stream->queue_mutex) {
> - size = iov_size(elem->out_sg, elem->out_num) - msg_sz;
> + size = iov_size(elem->out_sg, elem->out_num) - msg_sz;
>
> - buffer = g_malloc0(sizeof(VirtIOSoundPCMBuffer) + size);
> - buffer->elem = elem;
> - buffer->populated = false;
> - buffer->vq = vq;
> - buffer->size = size;
> - buffer->offset = 0;
> + buffer = g_malloc0(sizeof(VirtIOSoundPCMBuffer) + size);
> + buffer->elem = elem;
> + buffer->populated = false;
> + buffer->vq = vq;
> + buffer->size = size;
> + buffer->offset = 0;
>
> - QSIMPLEQ_INSERT_TAIL(&stream->queue, buffer, entry);
> - }
> + QSIMPLEQ_INSERT_TAIL(&stream->queue, buffer, entry);
> continue;
>
> tx_err:
> - WITH_QEMU_LOCK_GUARD(&stream->queue_mutex) {
> - must_empty_invalid_queue = true;
> - buffer = g_malloc0(sizeof(VirtIOSoundPCMBuffer));
> - buffer->elem = elem;
> - buffer->vq = vq;
> - QSIMPLEQ_INSERT_TAIL(&stream->invalid, buffer, entry);
> - }
> + must_empty_invalid_queue = true;
> + buffer = g_malloc0(sizeof(VirtIOSoundPCMBuffer));
> + buffer->elem = elem;
> + buffer->vq = vq;
> + QSIMPLEQ_INSERT_TAIL(&stream->invalid, buffer, entry);
> }
>
> if (must_empty_invalid_queue) {
> @@ -1005,26 +985,23 @@ static void virtio_snd_handle_rx_xfer(VirtIODevice
> *vdev, VirtQueue *vq)
> if (stream == NULL || stream->info.direction != VIRTIO_SND_D_INPUT) {
> goto rx_err;
> }
> - WITH_QEMU_LOCK_GUARD(&stream->queue_mutex) {
> - size = iov_size(elem->in_sg, elem->in_num) -
> - sizeof(virtio_snd_pcm_status);
> - buffer = g_malloc0(sizeof(VirtIOSoundPCMBuffer) + size);
> - buffer->elem = elem;
> - buffer->vq = vq;
> - buffer->size = 0;
> - buffer->offset = 0;
> - QSIMPLEQ_INSERT_TAIL(&stream->queue, buffer, entry);
> - }
> + size = iov_size(elem->in_sg, elem->in_num) -
> + sizeof(virtio_snd_pcm_status);
> + buffer = g_malloc0(sizeof(VirtIOSoundPCMBuffer) + size);
> + buffer->elem = elem;
> + buffer->vq = vq;
> + buffer->size = 0;
> + buffer->offset = 0;
> + QSIMPLEQ_INSERT_TAIL(&stream->queue, buffer, entry);
> continue;
>
> rx_err:
> - WITH_QEMU_LOCK_GUARD(&stream->queue_mutex) {
> - must_empty_invalid_queue = true;
> - buffer = g_malloc0(sizeof(VirtIOSoundPCMBuffer));
> - buffer->elem = elem;
> - buffer->vq = vq;
> - QSIMPLEQ_INSERT_TAIL(&stream->invalid, buffer, entry);
> - }
> + must_empty_invalid_queue = true;
> + buffer = g_malloc0(sizeof(VirtIOSoundPCMBuffer));
> + buffer->elem = elem;
> + buffer->vq = vq;
> + QSIMPLEQ_INSERT_TAIL(&stream->invalid, buffer, entry);
> +
> }
>
> if (must_empty_invalid_queue) {
> @@ -1122,7 +1099,6 @@ static void virtio_snd_realize(DeviceState *dev, Error
> **errp)
> virtio_add_queue(vdev, 64, virtio_snd_handle_tx_xfer);
> vsnd->queues[VIRTIO_SND_VQ_RX] =
> virtio_add_queue(vdev, 64, virtio_snd_handle_rx_xfer);
> - qemu_mutex_init(&vsnd->cmdq_mutex);
> QTAILQ_INIT(&vsnd->cmdq);
>
> for (uint32_t i = 0; i < vsnd->snd_conf.streams; i++) {
> @@ -1182,50 +1158,48 @@ static void virtio_snd_pcm_out_cb(void *data, int
> available)
> VirtIOSoundPCMBuffer *buffer;
> size_t size;
>
> - WITH_QEMU_LOCK_GUARD(&stream->queue_mutex) {
> - while (!QSIMPLEQ_EMPTY(&stream->queue)) {
> - buffer = QSIMPLEQ_FIRST(&stream->queue);
> - if (!virtio_queue_ready(buffer->vq)) {
> - return;
> + while (!QSIMPLEQ_EMPTY(&stream->queue)) {
> + buffer = QSIMPLEQ_FIRST(&stream->queue);
> + if (!virtio_queue_ready(buffer->vq)) {
> + return;
> + }
> + if (!stream->active) {
> + /* Stream has stopped, so do not perform AUD_write. */
> + return_tx_buffer(stream, buffer);
> + continue;
> + }
> + if (!buffer->populated) {
> + iov_to_buf(buffer->elem->out_sg,
> + buffer->elem->out_num,
> + sizeof(virtio_snd_pcm_xfer),
> + buffer->data,
> + buffer->size);
> + buffer->populated = true;
> + }
> + for (;;) {
> + size = AUD_write(stream->voice.out,
> + buffer->data + buffer->offset,
> + MIN(buffer->size, available));
> + assert(size <= MIN(buffer->size, available));
> + if (size == 0) {
> + /* break out of both loops */
> + available = 0;
> + break;
> }
> - if (!stream->active) {
> - /* Stream has stopped, so do not perform AUD_write. */
> + buffer->size -= size;
> + buffer->offset += size;
> + available -= size;
> + if (buffer->size < 1) {
> return_tx_buffer(stream, buffer);
> - continue;
> - }
> - if (!buffer->populated) {
> - iov_to_buf(buffer->elem->out_sg,
> - buffer->elem->out_num,
> - sizeof(virtio_snd_pcm_xfer),
> - buffer->data,
> - buffer->size);
> - buffer->populated = true;
> - }
> - for (;;) {
> - size = AUD_write(stream->voice.out,
> - buffer->data + buffer->offset,
> - MIN(buffer->size, available));
> - assert(size <= MIN(buffer->size, available));
> - if (size == 0) {
> - /* break out of both loops */
> - available = 0;
> - break;
> - }
> - buffer->size -= size;
> - buffer->offset += size;
> - available -= size;
> - if (buffer->size < 1) {
> - return_tx_buffer(stream, buffer);
> - break;
> - }
> - if (!available) {
> - break;
> - }
> + break;
> }
> if (!available) {
> break;
> }
> }
> + if (!available) {
> + break;
> + }
> }
> }
>
> @@ -1276,41 +1250,39 @@ static void virtio_snd_pcm_in_cb(void *data, int
> available)
> VirtIOSoundPCMBuffer *buffer;
> size_t size;
>
> - WITH_QEMU_LOCK_GUARD(&stream->queue_mutex) {
> - while (!QSIMPLEQ_EMPTY(&stream->queue)) {
> - buffer = QSIMPLEQ_FIRST(&stream->queue);
> - if (!virtio_queue_ready(buffer->vq)) {
> - return;
> + while (!QSIMPLEQ_EMPTY(&stream->queue)) {
> + buffer = QSIMPLEQ_FIRST(&stream->queue);
> + if (!virtio_queue_ready(buffer->vq)) {
> + return;
> + }
> + if (!stream->active) {
> + /* Stream has stopped, so do not perform AUD_read. */
> + return_rx_buffer(stream, buffer);
> + continue;
> + }
> +
> + for (;;) {
> + size = AUD_read(stream->voice.in,
> + buffer->data + buffer->size,
> + MIN(available, (stream->params.period_bytes -
> + buffer->size)));
> + if (!size) {
> + available = 0;
> + break;
> }
> - if (!stream->active) {
> - /* Stream has stopped, so do not perform AUD_read. */
> + buffer->size += size;
> + available -= size;
> + if (buffer->size >= stream->params.period_bytes) {
> return_rx_buffer(stream, buffer);
> - continue;
> - }
> -
> - for (;;) {
> - size = AUD_read(stream->voice.in,
> - buffer->data + buffer->size,
> - MIN(available, (stream->params.period_bytes -
> - buffer->size)));
> - if (!size) {
> - available = 0;
> - break;
> - }
> - buffer->size += size;
> - available -= size;
> - if (buffer->size >= stream->params.period_bytes) {
> - return_rx_buffer(stream, buffer);
> - break;
> - }
> - if (!available) {
> - break;
> - }
> + break;
> }
> if (!available) {
> break;
> }
> }
> + if (!available) {
> + break;
> + }
> }
> }
>
> @@ -1327,11 +1299,9 @@ static inline void
> virtio_snd_pcm_flush(VirtIOSoundPCMStream *stream)
> (stream->info.direction == VIRTIO_SND_D_OUTPUT) ? return_tx_buffer :
> return_rx_buffer;
>
> - WITH_QEMU_LOCK_GUARD(&stream->queue_mutex) {
> - while (!QSIMPLEQ_EMPTY(&stream->queue)) {
> - buffer = QSIMPLEQ_FIRST(&stream->queue);
> - cb(stream, buffer);
> - }
> + while (!QSIMPLEQ_EMPTY(&stream->queue)) {
> + buffer = QSIMPLEQ_FIRST(&stream->queue);
> + cb(stream, buffer);
> }
> }
>
> @@ -1351,7 +1321,6 @@ static void virtio_snd_unrealize(DeviceState *dev)
> if (stream) {
> virtio_snd_process_cmdq(stream->s);
> virtio_snd_pcm_close(stream);
> - qemu_mutex_destroy(&stream->queue_mutex);
> g_free(stream);
> }
> }
> @@ -1362,7 +1331,6 @@ static void virtio_snd_unrealize(DeviceState *dev)
> vsnd->pcm = NULL;
> }
> AUD_remove_card(&vsnd->card);
> - qemu_mutex_destroy(&vsnd->cmdq_mutex);
> virtio_delete_queue(vsnd->queues[VIRTIO_SND_VQ_CONTROL]);
> virtio_delete_queue(vsnd->queues[VIRTIO_SND_VQ_EVENT]);
> virtio_delete_queue(vsnd->queues[VIRTIO_SND_VQ_TX]);
> @@ -1376,12 +1344,10 @@ static void virtio_snd_reset(VirtIODevice *vdev)
> VirtIOSound *s = VIRTIO_SND(vdev);
> virtio_snd_ctrl_command *cmd;
>
> - WITH_QEMU_LOCK_GUARD(&s->cmdq_mutex) {
> - while (!QTAILQ_EMPTY(&s->cmdq)) {
> - cmd = QTAILQ_FIRST(&s->cmdq);
> - QTAILQ_REMOVE(&s->cmdq, cmd, next);
> - virtio_snd_ctrl_cmd_free(cmd);
> - }
> + while (!QTAILQ_EMPTY(&s->cmdq)) {
> + cmd = QTAILQ_FIRST(&s->cmdq);
> + QTAILQ_REMOVE(&s->cmdq, cmd, next);
> + virtio_snd_ctrl_cmd_free(cmd);
> }
> }
>
> diff --git a/include/hw/audio/virtio-snd.h b/include/hw/audio/virtio-snd.h
> index c3767f442b..ea6315f59b 100644
> --- a/include/hw/audio/virtio-snd.h
> +++ b/include/hw/audio/virtio-snd.h
> @@ -148,7 +148,6 @@ struct VirtIOSoundPCMStream {
> SWVoiceIn *in;
> SWVoiceOut *out;
> } voice;
> - QemuMutex queue_mutex;
> bool active;
> QSIMPLEQ_HEAD(, VirtIOSoundPCMBuffer) queue;
> QSIMPLEQ_HEAD(, VirtIOSoundPCMBuffer) invalid;
> @@ -220,9 +219,7 @@ struct VirtIOSound {
> QEMUSoundCard card;
> VMChangeStateEntry *vmstate;
> virtio_snd_config snd_conf;
> - QemuMutex cmdq_mutex;
> QTAILQ_HEAD(, virtio_snd_ctrl_command) cmdq;
> - bool processing_cmdq;
> };
>
> struct virtio_snd_ctrl_command {
> --
> 2.35.3
>
>
--
Marc-André Lureau
- [PATCH 00/10] virtio-sound migration part 1, Volker Rümelin, 2024/01/04
- [PATCH 01/10] hw/audio/virtio-sound: remove command and stream mutexes, Volker Rümelin, 2024/01/04
- Re: [PATCH 01/10] hw/audio/virtio-sound: remove command and stream mutexes,
Marc-André Lureau <=
- [PATCH 03/10] hw/audio/virtio-sound: split out virtio_snd_pcm_start_stop(), Volker Rümelin, 2024/01/04
- [PATCH 02/10] hw/audio/virtio-sound: allocate all streams in advance, Volker Rümelin, 2024/01/04
- [PATCH 06/10] hw/audio/virtio-sound: introduce virtio_snd_pcm_open(), Volker Rümelin, 2024/01/04
- [PATCH 05/10] hw/audio/virtio-sound: return correct command response size, Volker Rümelin, 2024/01/04
- [PATCH 04/10] hw/audio/virtio-sound: add stream state variable, Volker Rümelin, 2024/01/04