Re: [alsa-devel] [Xen-devel][PATCH 3/3] ALSA: xen-front: Use Xen common shared buffer implementation

Oleksandr Andrushchenko
2018-11-23T08:19:44Z

On 11/22/18 5:47 PM, Takashi Iwai wrote:
> On Thu, 22 Nov 2018 11:02:30 +0100,
> Oleksandr Andrushchenko wrote:
>> @@ -214,12 +221,19 @@ static void stream_clear(struct xen_snd_front_pcm_stream_info *stream)
>> stream->out_frames = 0;
>> atomic_set(&stream->hw_ptr, 0);
>> xen_snd_front_evtchnl_pair_clear(stream->evt_pair);
>> - xen_snd_front_shbuf_clear(&stream->sh_buf);
>> + memset(&stream->shbuf, 0, sizeof(stream->shbuf));
>> + stream->buffer = NULL;
>> + stream->buffer_sz = 0;
>> + stream->pages = NULL;
>> + stream->num_pages = 0;
>> }
>>
>> static void stream_free(struct xen_snd_front_pcm_stream_info *stream)
>> {
>> - xen_snd_front_shbuf_free(&stream->sh_buf);
>> + xen_front_pgdir_shbuf_unmap(&stream->shbuf);
>> + xen_front_pgdir_shbuf_free(&stream->shbuf);
>> + free_pages_exact(stream->buffer, stream->buffer_sz);
>> + kfree(stream->pages);
>> stream_clear(stream);
>> }
>>
>> @@ -421,10 +435,34 @@ static int alsa_close(struct snd_pcm_substream *substream)
>> return 0;
>> }
>>
>> +static int shbuf_setup_backstore(struct xen_snd_front_pcm_stream_info *stream,
>> + size_t buffer_sz)
>> +{
>> + int i;
>> +
>> + stream->buffer_sz = buffer_sz;
>> + stream->buffer = alloc_pages_exact(stream->buffer_sz, GFP_KERNEL);
>> + if (!stream->buffer)
>> + return -ENOMEM;
> This keeps the NULL stream->buffer, and then the caller goes to the
> error path via stream_free() which will lead to an Oops due to the
> unconditional call of free_pages_exact().

You are absolutely right, will fix

Thank you for catching this

>
>
> thanks,
>
> Takashi