Re: [PATCH v5 2/9] ALSA: virtio: add virtio sound driver

On Mon, 22 Feb 2021 16:34:37 +0100, Anton Yakovlev wrote:

+static int virtsnd_find_vqs(struct virtio_snd *snd) +{

• struct virtio_device *vdev = snd->vdev;
• vq_callback_t *callbacks[VIRTIO_SND_VQ_MAX] = {

• [VIRTIO_SND_VQ_EVENT] = virtsnd_event_notify_cb
  

• };
• const char *names[VIRTIO_SND_VQ_MAX] = {

Shouldn't be static? Also it's often const char * const names[] = { ... } unless you overwrite something.

+/**

• • virtsnd_reset_fn() - Kernel worker's function to reset the device.
• • @work: Reset device work.
• • Context: Process context.
• */

+static void virtsnd_reset_fn(struct work_struct *work) +{

• struct virtio_snd *snd =

• container_of(work, struct virtio_snd, reset_work);
  

• struct virtio_device *vdev = snd->vdev;
• struct device *dev = &vdev->dev;
• int rc;
• dev_info(dev, "sound device needs reset\n");
• /*

• * It seems that the only way to properly reset the device is to remove
  

• * and re-create the ALSA sound card device.
  

• */
  

• rc = device_reprobe(dev);
• if (rc)

• dev_err(dev, "failed to reprobe sound device: %d\n", rc);
  

Now I'm wondering whether it's safe to do that from this place. Basically device_reprobe() unbinds the device that releases the full resources once including the devm_* stuff. And this work itself is in a part of devm allocated resource, so it'll be released there. That said, we might hit use-after-free... This needs to be verified.

thanks,

Takashi