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

[Oleksandr Andrushchenko]

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(>hw_ptr, 0);
xen_snd_front_evtchnl_pair_clear(stream->evt_pair);
-   xen_snd_front_shbuf_clear(>sh_buf);
+   memset(>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(>sh_buf);
+   xen_front_pgdir_shbuf_unmap(>shbuf);
+   xen_front_pgdir_shbuf_free(>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

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

[Takashi Iwai]

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(>hw_ptr, 0);
>   xen_snd_front_evtchnl_pair_clear(stream->evt_pair);
> - xen_snd_front_shbuf_clear(>sh_buf);
> + memset(>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(>sh_buf);
> + xen_front_pgdir_shbuf_unmap(>shbuf);
> + xen_front_pgdir_shbuf_free(>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().


thanks,

Takashi
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