linux-kernel - Re: [Xen-devel][PATCH 1/2] xen/gntdev: Do not destroy context while dma-bufs are in use

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Date:   Fri, 15 Feb 2019 17:07:42 +0200
From:   Oleksandr Andrushchenko <andr2000@...il.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
        jgross@...e.com
Cc:     Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
Subject: Re: [Xen-devel][PATCH 1/2] xen/gntdev: Do not destroy context while
 dma-bufs are in use

On 2/15/19 5:03 PM, Boris Ostrovsky wrote:
> On 2/14/19 9:23 AM, Oleksandr Andrushchenko wrote:
>>   
>>   /* DMA buffer export support. */
>> @@ -311,6 +317,7 @@ static void dmabuf_exp_release(struct kref *kref)
>>   
>>   	dmabuf_exp_wait_obj_signal(gntdev_dmabuf->priv, gntdev_dmabuf);
>>   	list_del(&gntdev_dmabuf->next);
>> +	fput(gntdev_dmabuf->priv->filp);
>>   	kfree(gntdev_dmabuf);
>>   }
>>   
>> @@ -423,6 +430,7 @@ static int dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args *args)
>>   	mutex_lock(&args->dmabuf_priv->lock);
>>   	list_add(&gntdev_dmabuf->next, &args->dmabuf_priv->exp_list);
>>   	mutex_unlock(&args->dmabuf_priv->lock);
>> +	get_file(gntdev_dmabuf->priv->filp);
> Not fget()?
fget wants file descriptor [1] and returns struct file *,
but we already have struct file*, so I use get_file [2]
which does what I need - increments the reference counter
on the file
>
> -boris
>
>
[1] 
https://elixir.bootlin.com/linux/v5.0-rc6/source/include/linux/file.h#L46
[2] https://elixir.bootlin.com/linux/v5.0-rc6/source/include/linux/fs.h#L949