Messages in this thread | | | Subject | Re: [PATCH v5 2/9] ALSA: virtio: add virtio sound driver | From | Anton Yakovlev <> | Date | Thu, 25 Feb 2021 12:51:36 +0100 |
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On 25.02.2021 11:38, Takashi Iwai wrote: > 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?
Well, yes. Although in this particular case, I do not think it is that critical. :)
> Also it's often const char * const names[] = { ... } > unless you overwrite something.
I tried to use the same type names as in the function prototype. Otherwise the compiler or static analyzer may complain.
>> +/** >> + * 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.
It's safe. Suicide kernel workers are funny but possible things. Since the kernel itself (AFAIU) assumes such a situation and does not access the worker structure after the callback function call.
> thanks, > > Takashi >
-- Anton Yakovlev Senior Software Engineer
OpenSynergy GmbH Rotherstr. 20, 10245 Berlin
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