[PATCH v2 3/9] ALSA: virtio: handling control messages
From: Anton Yakovlev
Date: Sun Jan 24 2021 - 11:55:41 EST
The control queue can be used by different parts of the driver to send
commands to the device. Control messages can be either synchronous or
asynchronous. The lifetime of a message is controlled by a reference
count.
Introduce a module parameter to set the message completion timeout:
msg_timeout_ms [=1000]
Signed-off-by: Anton Yakovlev <anton.yakovlev@xxxxxxxxxxxxxxx>
---
sound/virtio/Makefile | 3 +-
sound/virtio/virtio_card.c | 20 +++
sound/virtio/virtio_card.h | 7 +
sound/virtio/virtio_ctl_msg.c | 293 ++++++++++++++++++++++++++++++++++
sound/virtio/virtio_ctl_msg.h | 122 ++++++++++++++
5 files changed, 444 insertions(+), 1 deletion(-)
create mode 100644 sound/virtio/virtio_ctl_msg.c
create mode 100644 sound/virtio/virtio_ctl_msg.h
diff --git a/sound/virtio/Makefile b/sound/virtio/Makefile
index 8c87ebb9982b..dc551e637441 100644
--- a/sound/virtio/Makefile
+++ b/sound/virtio/Makefile
@@ -3,5 +3,6 @@
obj-$(CONFIG_SND_VIRTIO) += virtio_snd.o
virtio_snd-objs := \
- virtio_card.o
+ virtio_card.o \
+ virtio_ctl_msg.o
diff --git a/sound/virtio/virtio_card.c b/sound/virtio/virtio_card.c
index 532d823fdf6f..955eadc2d858 100644
--- a/sound/virtio/virtio_card.c
+++ b/sound/virtio/virtio_card.c
@@ -24,6 +24,10 @@
#include "virtio_card.h"
+int msg_timeout_ms = MSEC_PER_SEC;
+module_param(msg_timeout_ms, int, 0644);
+MODULE_PARM_DESC(msg_timeout_ms, "Message completion timeout in milliseconds");
+
static void virtsnd_remove(struct virtio_device *vdev);
/**
@@ -125,6 +129,7 @@ static int virtsnd_find_vqs(struct virtio_snd *snd)
unsigned int n = 0;
int rc;
+ callbacks[VIRTIO_SND_VQ_CONTROL] = virtsnd_ctl_notify_cb;
callbacks[VIRTIO_SND_VQ_EVENT] = virtsnd_event_notify_cb;
rc = virtio_find_vqs(vdev, VIRTIO_SND_VQ_MAX, vqs, callbacks, names,
@@ -193,6 +198,15 @@ static void virtsnd_disable_vqs(struct virtio_snd *snd)
if (queue->vqueue)
virtqueue_disable_cb(queue->vqueue);
queue->vqueue = NULL;
+ /* Cancel all pending requests for the control queue */
+ if (i == VIRTIO_SND_VQ_CONTROL) {
+ struct virtio_snd_msg *msg;
+ struct virtio_snd_msg *next;
+
+ list_for_each_entry_safe(msg, next, &snd->ctl_msgs,
+ list)
+ virtsnd_ctl_msg_complete(snd, msg);
+ }
spin_unlock_irqrestore(&queue->lock, flags);
}
@@ -283,6 +297,11 @@ static int virtsnd_validate(struct virtio_device *vdev)
return -EINVAL;
}
+ if (!msg_timeout_ms) {
+ dev_err(&vdev->dev, "msg_timeout_ms value cannot be zero\n");
+ return -EINVAL;
+ }
+
return 0;
}
@@ -305,6 +324,7 @@ static int virtsnd_probe(struct virtio_device *vdev)
snd->vdev = vdev;
INIT_WORK(&snd->reset_work, virtsnd_reset_fn);
+ INIT_LIST_HEAD(&snd->ctl_msgs);
vdev->priv = snd;
diff --git a/sound/virtio/virtio_card.h b/sound/virtio/virtio_card.h
index 10084abaaf18..37b734a92134 100644
--- a/sound/virtio/virtio_card.h
+++ b/sound/virtio/virtio_card.h
@@ -23,6 +23,8 @@
#include <sound/core.h>
#include <uapi/linux/virtio_snd.h>
+#include "virtio_ctl_msg.h"
+
/**
* struct virtio_snd_queue - Virtqueue wrapper structure.
* @lock: Used to synchronize access to a virtqueue.
@@ -39,6 +41,7 @@ struct virtio_snd_queue {
* @queues: Virtqueue wrappers.
* @reset_work: Reset device work.
* @card: ALSA sound card.
+ * @ctl_msgs: Pending control request list.
* @event_msgs: Device events.
*/
struct virtio_snd {
@@ -46,9 +49,13 @@ struct virtio_snd {
struct virtio_snd_queue queues[VIRTIO_SND_VQ_MAX];
struct work_struct reset_work;
struct snd_card *card;
+ struct list_head ctl_msgs;
struct virtio_snd_event *event_msgs;
};
+/* Message completion timeout in milliseconds (module parameter). */
+extern int msg_timeout_ms;
+
static inline struct virtio_snd_queue *
virtsnd_control_queue(struct virtio_snd *snd)
{
diff --git a/sound/virtio/virtio_ctl_msg.c b/sound/virtio/virtio_ctl_msg.c
new file mode 100644
index 000000000000..c1701756bc32
--- /dev/null
+++ b/sound/virtio/virtio_ctl_msg.c
@@ -0,0 +1,293 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Sound card driver for virtio
+ * Copyright (C) 2020 OpenSynergy GmbH
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+#include <linux/moduleparam.h>
+#include <linux/virtio_config.h>
+
+#include "virtio_card.h"
+#include "virtio_ctl_msg.h"
+
+/**
+ * virtsnd_ctl_msg_alloc_ext() - Allocate and initialize a control message.
+ * @vdev: VirtIO parent device.
+ * @request_size: Size of request header (pointed to by sg_request field).
+ * @response_size: Size of response header (pointed to by sg_response field).
+ * @sgs: Additional data to attach to the message (may be NULL).
+ * @out_sgs: Number of scattergather elements to attach to the request header.
+ * @in_sgs: Number of scattergather elements to attach to the response header.
+ * @gfp: Kernel flags for memory allocation.
+ *
+ * The message will be automatically freed when the ref_count value is 0.
+ *
+ * Context: Any context. May sleep if @gfp flags permit.
+ * Return: Allocated message on success, ERR_PTR(-errno) on failure.
+ */
+struct virtio_snd_msg *virtsnd_ctl_msg_alloc_ext(struct virtio_device *vdev,
+ size_t request_size,
+ size_t response_size,
+ struct scatterlist *sgs,
+ unsigned int out_sgs,
+ unsigned int in_sgs, gfp_t gfp)
+{
+ struct virtio_snd_msg *msg;
+ size_t msg_size =
+ sizeof(*msg) + (1 + out_sgs + 1 + in_sgs) * sizeof(*msg->sgs);
+ unsigned int i;
+
+ msg = devm_kzalloc(&vdev->dev, msg_size + request_size + response_size,
+ gfp);
+ if (!msg)
+ return ERR_PTR(-ENOMEM);
+
+ sg_init_one(&msg->sg_request, (u8 *)msg + msg_size, request_size);
+ sg_init_one(&msg->sg_response, (u8 *)msg + msg_size + request_size,
+ response_size);
+
+ INIT_LIST_HEAD(&msg->list);
+ init_completion(&msg->notify);
+ atomic_set(&msg->ref_count, 1);
+
+ msg->sgs[msg->out_sgs++] = &msg->sg_request;
+ if (sgs)
+ for (i = 0; i < out_sgs; ++i)
+ msg->sgs[msg->out_sgs++] = &sgs[i];
+
+ msg->sgs[msg->out_sgs + msg->in_sgs++] = &msg->sg_response;
+ if (sgs)
+ for (i = out_sgs; i < out_sgs + in_sgs; ++i)
+ msg->sgs[msg->out_sgs + msg->in_sgs++] = &sgs[i];
+
+ return msg;
+}
+
+/**
+ * virtsnd_ctl_msg_send() - Send an (asynchronous) control message.
+ * @snd: VirtIO sound device.
+ * @msg: Control message.
+ *
+ * If a message is failed to be enqueued, it will be deleted. If message content
+ * is still needed, the caller must additionally to virtsnd_ctl_msg_ref/unref()
+ * it.
+ *
+ * Context: Any context. Takes and releases the control queue spinlock.
+ * Return: 0 on success, -errno on failure.
+ */
+int virtsnd_ctl_msg_send(struct virtio_snd *snd, struct virtio_snd_msg *msg)
+{
+ struct virtio_device *vdev = snd->vdev;
+ struct virtio_snd_queue *queue = virtsnd_control_queue(snd);
+ struct virtio_snd_hdr *response = sg_virt(&msg->sg_response);
+ bool notify = false;
+ unsigned long flags;
+ int rc = -EIO;
+
+ /* Set the default status in case the message was not sent or was
+ * canceled.
+ */
+ response->code = cpu_to_virtio32(vdev, VIRTIO_SND_S_IO_ERR);
+
+ spin_lock_irqsave(&queue->lock, flags);
+ if (queue->vqueue) {
+ rc = virtqueue_add_sgs(queue->vqueue, msg->sgs, msg->out_sgs,
+ msg->in_sgs, msg, GFP_ATOMIC);
+ if (!rc) {
+ notify = virtqueue_kick_prepare(queue->vqueue);
+ list_add_tail(&msg->list, &snd->ctl_msgs);
+ }
+ }
+ spin_unlock_irqrestore(&queue->lock, flags);
+
+ if (!rc) {
+ if (!notify || virtqueue_notify(queue->vqueue))
+ return 0;
+
+ spin_lock_irqsave(&queue->lock, flags);
+ list_del(&msg->list);
+ spin_unlock_irqrestore(&queue->lock, flags);
+ }
+
+ virtsnd_ctl_msg_unref(snd->vdev, msg);
+
+ return -EIO;
+}
+
+/**
+ * virtsnd_ctl_msg_send_sync() - Send a (synchronous) control message.
+ * @snd: VirtIO sound device.
+ * @msg: Control message.
+ *
+ * After returning from this function, the message will be deleted. If message
+ * content is still needed, the caller must additionally to
+ * virtsnd_ctl_msg_ref/unref() it.
+ *
+ * The msg_timeout_ms module parameter defines the message completion timeout.
+ * If the message is not completed within this time, the function will return an
+ * error.
+ *
+ * Context: Any context. Takes and releases the control queue spinlock.
+ * Return: 0 on success, -errno on failure.
+ *
+ * The return value is a message status code (VIRTIO_SND_S_XXX) converted to an
+ * appropriate -errno value.
+ */
+int virtsnd_ctl_msg_send_sync(struct virtio_snd *snd,
+ struct virtio_snd_msg *msg)
+{
+ struct virtio_device *vdev = snd->vdev;
+ unsigned int js = msecs_to_jiffies(msg_timeout_ms);
+ struct virtio_snd_hdr *response;
+ int rc;
+
+ virtsnd_ctl_msg_ref(vdev, msg);
+
+ rc = virtsnd_ctl_msg_send(snd, msg);
+ if (rc)
+ goto on_failure;
+
+ rc = wait_for_completion_interruptible_timeout(&msg->notify, js);
+ if (rc <= 0) {
+ if (!rc) {
+ struct virtio_snd_hdr *request =
+ sg_virt(&msg->sg_request);
+
+ dev_err(&vdev->dev,
+ "control message (0x%08x) timeout\n",
+ le32_to_cpu(request->code));
+ rc = -EIO;
+ }
+
+ goto on_failure;
+ }
+
+ response = sg_virt(&msg->sg_response);
+
+ switch (le32_to_cpu(response->code)) {
+ case VIRTIO_SND_S_OK:
+ rc = 0;
+ break;
+ case VIRTIO_SND_S_BAD_MSG:
+ rc = -EINVAL;
+ break;
+ case VIRTIO_SND_S_NOT_SUPP:
+ rc = -EOPNOTSUPP;
+ break;
+ case VIRTIO_SND_S_IO_ERR:
+ rc = -EIO;
+ break;
+ default:
+ rc = -EPERM;
+ break;
+ }
+
+on_failure:
+ virtsnd_ctl_msg_unref(vdev, msg);
+
+ return rc;
+}
+
+/**
+ * virtsnd_ctl_msg_complete() - Complete a control message.
+ * @snd: VirtIO sound device.
+ * @msg: Control message.
+ *
+ * Context: Any context.
+ */
+void virtsnd_ctl_msg_complete(struct virtio_snd *snd,
+ struct virtio_snd_msg *msg)
+{
+ list_del(&msg->list);
+ complete(&msg->notify);
+
+ virtsnd_ctl_msg_unref(snd->vdev, msg);
+}
+
+/**
+ * virtsnd_ctl_query_info() - Query the item configuration from the device.
+ * @snd: VirtIO sound device.
+ * @command: Control request code (VIRTIO_SND_R_XXX_INFO).
+ * @start_id: Item start identifier.
+ * @count: Item count to query.
+ * @size: Item information size in bytes.
+ * @info: Buffer for storing item information.
+ *
+ * Context: Any context that permits to sleep.
+ * Return: 0 on success, -errno on failure.
+ */
+int virtsnd_ctl_query_info(struct virtio_snd *snd, int command, int start_id,
+ int count, size_t size, void *info)
+{
+ struct virtio_device *vdev = snd->vdev;
+ struct virtio_snd_msg *msg;
+ struct virtio_snd_query_info *query;
+ struct scatterlist sg;
+
+ sg_init_one(&sg, info, count * size);
+
+ msg = virtsnd_ctl_msg_alloc_ext(vdev, sizeof(*query),
+ sizeof(struct virtio_snd_hdr), &sg, 0,
+ 1, GFP_KERNEL);
+ if (IS_ERR(msg))
+ return PTR_ERR(msg);
+
+ query = sg_virt(&msg->sg_request);
+ query->hdr.code = cpu_to_virtio32(vdev, command);
+ query->start_id = cpu_to_virtio32(vdev, start_id);
+ query->count = cpu_to_virtio32(vdev, count);
+ query->size = cpu_to_virtio32(vdev, size);
+
+ return virtsnd_ctl_msg_send_sync(snd, msg);
+}
+
+/**
+ * virtsnd_ctl_notify_cb() - Process all completed control messages.
+ * @vqueue: Underlying control virtqueue.
+ *
+ * This callback function is called upon a vring interrupt request from the
+ * device.
+ *
+ * Context: Interrupt context. Takes and releases the control queue spinlock.
+ */
+void virtsnd_ctl_notify_cb(struct virtqueue *vqueue)
+{
+ struct virtio_snd *snd = vqueue->vdev->priv;
+ struct virtio_snd_queue *queue = virtsnd_control_queue(snd);
+ unsigned long flags;
+
+ spin_lock_irqsave(&queue->lock, flags);
+ while (queue->vqueue) {
+ virtqueue_disable_cb(queue->vqueue);
+
+ for (;;) {
+ struct virtio_snd_msg *msg;
+ u32 length;
+
+ msg = virtqueue_get_buf(queue->vqueue, &length);
+ if (!msg)
+ break;
+
+ virtsnd_ctl_msg_complete(snd, msg);
+ }
+
+ if (unlikely(virtqueue_is_broken(queue->vqueue)))
+ break;
+
+ if (virtqueue_enable_cb(queue->vqueue))
+ break;
+ }
+ spin_unlock_irqrestore(&queue->lock, flags);
+}
diff --git a/sound/virtio/virtio_ctl_msg.h b/sound/virtio/virtio_ctl_msg.h
new file mode 100644
index 000000000000..0f8de8f2fd2d
--- /dev/null
+++ b/sound/virtio/virtio_ctl_msg.h
@@ -0,0 +1,122 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Sound card driver for virtio
+ * Copyright (C) 2020 OpenSynergy GmbH
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef VIRTIO_SND_MSG_H
+#define VIRTIO_SND_MSG_H
+
+#include <linux/atomic.h>
+#include <linux/virtio.h>
+
+struct virtio_snd;
+
+/**
+ * struct virtio_snd_msg - Control message.
+ * @sg_request: Scattergather element containing a device request (header).
+ * @sg_response: Scattergather element containing a device response (status).
+ * @list: Pending message list entry.
+ * @notify: Request completed notification.
+ * @ref_count: Reference count used to manage a message lifetime.
+ * @out_sgs: Number of read-only sg elements in the sgs array.
+ * @in_sgs: Number of write-only sg elements in the sgs array.
+ * @sgs: Array of sg elements to add to the control virtqueue.
+ */
+struct virtio_snd_msg {
+/* public: */
+ struct scatterlist sg_request;
+ struct scatterlist sg_response;
+/* private: internal use only */
+ struct list_head list;
+ struct completion notify;
+ atomic_t ref_count;
+ unsigned int out_sgs;
+ unsigned int in_sgs;
+ struct scatterlist *sgs[0];
+};
+
+/**
+ * virtsnd_ctl_msg_ref() - Increment reference counter for the message.
+ * @vdev: VirtIO parent device.
+ * @msg: Control message.
+ *
+ * Context: Any context.
+ */
+static inline void virtsnd_ctl_msg_ref(struct virtio_device *vdev,
+ struct virtio_snd_msg *msg)
+{
+ atomic_inc(&msg->ref_count);
+}
+
+/**
+ * virtsnd_ctl_msg_unref() - Decrement reference counter for the message.
+ * @vdev: VirtIO parent device.
+ * @msg: Control message.
+ *
+ * The message will be freed when the ref_count value is 0.
+ *
+ * Context: Any context.
+ */
+static inline void virtsnd_ctl_msg_unref(struct virtio_device *vdev,
+ struct virtio_snd_msg *msg)
+{
+ if (!atomic_dec_return(&msg->ref_count))
+ devm_kfree(&vdev->dev, msg);
+}
+
+struct virtio_snd_msg *virtsnd_ctl_msg_alloc_ext(struct virtio_device *vdev,
+ size_t request_size,
+ size_t response_size,
+ struct scatterlist *sgs,
+ unsigned int out_sgs,
+ unsigned int in_sgs,
+ gfp_t gfp);
+
+/**
+ * virtsnd_ctl_msg_alloc() - Simplified control message allocation.
+ * @vdev: VirtIO parent device.
+ * @request_size: Size of request header (pointed to by sg_request field).
+ * @response_size: Size of response header (pointed to by sg_response field).
+ * @gfp: Kernel flags for memory allocation.
+ *
+ * The message will be automatically freed when the ref_count value is 0.
+ *
+ * Context: Any context. May sleep if @gfp flags permit.
+ * Return: Allocated message on success, ERR_PTR(-errno) on failure.
+ */
+static inline
+struct virtio_snd_msg *virtsnd_ctl_msg_alloc(struct virtio_device *vdev,
+ size_t request_size,
+ size_t response_size, gfp_t gfp)
+{
+ return virtsnd_ctl_msg_alloc_ext(vdev, request_size, response_size,
+ NULL, 0, 0, gfp);
+}
+
+int virtsnd_ctl_msg_send(struct virtio_snd *snd, struct virtio_snd_msg *msg);
+
+int virtsnd_ctl_msg_send_sync(struct virtio_snd *snd,
+ struct virtio_snd_msg *msg);
+
+void virtsnd_ctl_msg_complete(struct virtio_snd *snd,
+ struct virtio_snd_msg *msg);
+
+int virtsnd_ctl_query_info(struct virtio_snd *snd, int command, int start_id,
+ int count, size_t size, void *info);
+
+void virtsnd_ctl_notify_cb(struct virtqueue *vqueue);
+
+#endif /* VIRTIO_SND_MSG_H */
--
2.30.0