buf: buffer free "virtual destructor"

struct sof_audio_buffer is a "base class" in
a meaning of C++ of all buffers in SOF (currently
comp_buffer and ring_buffer). Freeing of memory was
based on indirect assumption that struct sof_audio_buffer
is a very first field of the buffer structure

this commit moves freeing of buffer to a method
specific for each buffer type, enforcing that proper
pointer will be used regardless of buffer structure

Signed-off-by: Marcin Szkudlinski <marcin.szkudlinski@intel.com>

Author: marcinszkudlinski

src/audio/buffers/audio_buffer.c

@@ -92,9 +92,8 @@ void audio_buffer_free(struct sof_audio_buffer *buffer)
 	audio_buffer_free(buffer->secondary_buffer_sink);
 	audio_buffer_free(buffer->secondary_buffer_source);
 #endif /* CONFIG_PIPELINE_2_0 */
-	if (buffer->ops->free)
-		buffer->ops->free(buffer);
-	rfree(buffer);
+	/* "virtual destructor": free the buffer internals and buffer memory */
+	buffer->ops->free(buffer);
 }
 
 static
@@ -196,6 +195,7 @@ void audio_buffer_init(struct sof_audio_buffer *buffer, uint32_t buffer_type, bo
 	CORE_CHECK_STRUCT_INIT(&buffer, is_shared);
 	buffer->buffer_type = buffer_type;
 	buffer->ops = audio_buffer_ops;
+	assert(audio_buffer_ops->free);
 	buffer->audio_stream_params = audio_stream_params;
 	buffer->is_shared = is_shared;
 

src/audio/buffers/comp_buffer.c

@@ -158,6 +158,7 @@ static void comp_buffer_free(struct sof_audio_buffer *audio_buffer)
 	notifier_unregister_all(NULL, buffer);
 
 	rfree(buffer->stream.addr);
+	rfree(buffer);
 }
 
 static struct source_ops comp_buffer_source_ops = {

src/audio/buffers/ring_buffer.c

@@ -96,6 +96,7 @@ static void ring_buffer_free(struct sof_audio_buffer *audio_buffer)
 			container_of(audio_buffer, struct ring_buffer, audio_buffer);
 
 	rfree((__sparse_force void *)ring_buffer->_data_buffer);
+	rfree(ring_buffer);
 }
 
 static void ring_buffer_reset(struct sof_audio_buffer *audio_buffer)

src/include/sof/audio/audio_buffer.h

@@ -21,8 +21,8 @@ struct sof_audio_buffer;
 struct audio_buffer_ops {
 	/**
 	 * @brief this method must free all structures allocated by buffer implementation
-	 *	  it must not free the buffer memory itself
-	 *	  OPTIONAL
+	 *	  and the buffer itself
+	 *	  OBLIGATORY
 	 */
 	void (*free)(struct sof_audio_buffer *buffer);