linux-kernel - Re: [PATCH] xen: add new hypercall buffer mapping device

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Date:   Fri, 15 Jun 2018 17:26:05 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org
Subject: Re: [PATCH] xen: add new hypercall buffer mapping device

On 15/06/18 16:43, Boris Ostrovsky wrote:
> On 06/15/2018 09:17 AM, Juergen Gross wrote:
>> +static int privcmd_buf_mmap(struct file *file, struct vm_area_struct *vma)
>> +{
>> +	struct privcmd_buf_private *file_priv = file->private_data;
>> +	struct privcmd_buf_vma_private *vma_priv;
>> +	unsigned int count = vma_pages(vma);
>> +	unsigned int i;
>> +	int ret = 0;
>> +
>> +	if (!(vma->vm_flags & VM_SHARED)) {
>> +		pr_err("Mapping must be shared\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	if (file_priv->allocated + count > limit) {
>> +		pr_err("Mapping limit reached!\n");
>> +		return -ENOSPC;
> 
> 
> This error (which I thought should have been E2BIG) is not in the list
> of allowed error codes (per man page). I think it it's either EINVAL or
> ENOMEM (EINVAL seems more appropriate to me).

Okay.

> I am also not sure about pr_err as the caller can force it (although
> presumably the file is only accessible to superuser).

I've already replied to Jan: I'll drop the messages.


Juergen