linux-kernel - Re: [Xen-devel] [PATCH 5/9] drm/xen/xen_drm_front_gem.c: Convert to use vm_insert

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Message-ID: <c76fc2fa-d08b-7db3-5693-d9c303cd7126@gmail.com>
Date:   Mon, 19 Nov 2018 13:02:46 +0200
From:   Oleksandr Andrushchenko <andr2000@...il.com>
To:     Souptick Joarder <jrdr.linux@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>,
        Michal Hocko <mhocko@...e.com>,
        oleksandr_andrushchenko@...m.com, airlied@...ux.ie,
        Linux-MM <linux-mm@...ck.org>, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, xen-devel@...ts.xen.org
Subject: Re: [Xen-devel] [PATCH 5/9] drm/xen/xen_drm_front_gem.c: Convert to
 use vm_insert_range

On 11/19/18 12:42 PM, Souptick Joarder wrote:
> On Mon, Nov 19, 2018 at 3:22 PM Oleksandr Andrushchenko
> <andr2000@...il.com> wrote:
>> On 11/15/18 5:49 PM, Souptick Joarder wrote:
>>> Convert to use vm_insert_range() to map range of kernel
>>> memory to user vma.
>>>
>>> Signed-off-by: Souptick Joarder <jrdr.linux@...il.com>
>>> Reviewed-by: Matthew Wilcox <willy@...radead.org>
>>> ---
>>>    drivers/gpu/drm/xen/xen_drm_front_gem.c | 20 ++++++--------------
>>>    1 file changed, 6 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.c b/drivers/gpu/drm/xen/xen_drm_front_gem.c
>>> index 47ff019..a3eade6 100644
>>> --- a/drivers/gpu/drm/xen/xen_drm_front_gem.c
>>> +++ b/drivers/gpu/drm/xen/xen_drm_front_gem.c
>>> @@ -225,8 +225,7 @@ struct drm_gem_object *
>>>    static int gem_mmap_obj(struct xen_gem_object *xen_obj,
>>>                        struct vm_area_struct *vma)
>>>    {
>>> -     unsigned long addr = vma->vm_start;
>>> -     int i;
>>> +     int err;
>> I would love to keep ret, not err
> Sure, will add it in v2.
> But I think, err is more appropriate here.

I used "ret" throughout the driver, so this is just to remain consistent:

grep -rnw err drivers/gpu/drm/xen/ | wc -l
0
grep -rnw ret drivers/gpu/drm/xen/ | wc -l
204

>>>        /*
>>>         * clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the
>>> @@ -247,18 +246,11 @@ static int gem_mmap_obj(struct xen_gem_object *xen_obj,
>>>         * FIXME: as we insert all the pages now then no .fault handler must
>>>         * be called, so don't provide one
>>>         */
>>> -     for (i = 0; i < xen_obj->num_pages; i++) {
>>> -             int ret;
>>> -
>>> -             ret = vm_insert_page(vma, addr, xen_obj->pages[i]);
>>> -             if (ret < 0) {
>>> -                     DRM_ERROR("Failed to insert pages into vma: %d\n", ret);
>>> -                     return ret;
>>> -             }
>>> -
>>> -             addr += PAGE_SIZE;
>>> -     }
>>> -     return 0;
>>> +     err = vm_insert_range(vma, vma->vm_start, xen_obj->pages,
>>> +                             xen_obj->num_pages);
>>> +     if (err < 0)
>>> +             DRM_ERROR("Failed to insert pages into vma: %d\n", err);
>>> +     return err;
>>>    }
>>>
>>>    int xen_drm_front_gem_mmap(struct file *filp, struct vm_area_struct *vma)
>> With the above fixed,
>>
>> Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
>>