浅析alsa声卡驱动snd_pcm_oss_plugin_clear函数

static int snd_pcm_oss_plugin_clear(struct snd_pcm_substream *substream)
{
    struct snd_pcm_runtime *runtime = substream->runtime;
    struct snd_pcm_plugin *plugin, *next;
    
    plugin = runtime->oss.plugin_first;
    while (plugin) {
        next = plugin->next;
        snd_pcm_plugin_free(plugin); // 释放链表上所有plugin
        plugin = next;
    }
    runtime->oss.plugin_first = runtime->oss.plugin_last = NULL; // 清空oss.plugin_first链表[luther.gliethttp]
    return 0;
}

int snd_pcm_plugin_free(struct snd_pcm_plugin *plugin)
{
    if (! plugin)
        return 0;
    if (plugin->private_free)
        plugin->private_free(plugin);
    kfree(plugin->buf_channels); // 释放plugin->buf_channels,它可以等于0
    vfree(plugin->buf); // 释放plugin->buf,它可以等于0
    kfree(plugin); // 释放plugin内存
    return 0;
}