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virtio-snd: rewrite invalid tx/rx message handling

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The current handling of invalid virtqueue elements inside the TX/RX virt
queue handlers is wrong.

They are added in a per-stream invalid queue to be processed after the
handler is done examining each message, but the invalid message might
not be specifying any stream_id; which means it's invalid to add it to
any stream->invalid queue since stream could be NULL at this point.

This commit moves the invalid queue to the VirtIOSound struct which
guarantees there will always be a valid temporary place to store them
inside the tx/rx handlers. The queue will be emptied before the handler
returns, so the queue must be empty at any other point of the device's
lifetime.

Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Message-Id: <virtio-snd-rewrite-invalid-tx-rx-message-handling-v1.manos.pitsidianakis@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Manos Pitsidianakis 2024-03-24 12:04:59 +02:00 • committed by Michael S. Tsirkin
parent a45f09935c
commit 731655f87f
2 changed files with 77 additions and 76 deletions
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16
include/hw/audio/virtio-snd.h
View file

@ -151,7 +151,6 @@ struct VirtIOSoundPCMStream {
QemuMutex queue_mutex;
bool active;
QSIMPLEQ_HEAD(, VirtIOSoundPCMBuffer) queue;
QSIMPLEQ_HEAD(, VirtIOSoundPCMBuffer) invalid;
};
/*
@ -223,6 +222,21 @@ struct VirtIOSound {
QemuMutex cmdq_mutex;
QTAILQ_HEAD(, virtio_snd_ctrl_command) cmdq;
bool processing_cmdq;
/*
* Convenience queue to keep track of invalid tx/rx queue messages inside
* the tx/rx callbacks.
*
* In the callbacks as a first step we are emptying the virtqueue to handle
* each message and we cannot add an invalid message back to the queue: we
* would re-process it in subsequent loop iterations.
*
* Instead, we add them to this queue and after finishing examining every
* virtqueue element, we inform the guest for each invalid message.
*
* This queue must be empty at all times except for inside the tx/rx
* callbacks.
*/
QSIMPLEQ_HEAD(, VirtIOSoundPCMBuffer) invalid;
};
struct virtio_snd_ctrl_command {