linux-kernel - [PATCH 2/2] auxdisplay/ht16k33.c: Convert to use vm_map_pages

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Date:   Mon, 20 May 2019 21:00:58 +0530
From:   Souptick Joarder <jrdr.linux@...il.com>
To:     miguel.ojeda.sandonis@...il.com, robin@...tonic.nl
Cc:     linux-kernel@...r.kernel.org, willy@...radead.org,
        Souptick Joarder <jrdr.linux@...il.com>
Subject: [PATCH 2/2] auxdisplay/ht16k33.c: Convert to use vm_map_pages_zero()

While using mmap, the incorrect value of length and vm_pgoff are
ignored and this driver go ahead with mapping fbdev.buffer
to user vma.

Convert vm_insert_pages() to use vm_map_pages_zero(). We could later
"fix" these drivers to behave according to the normal vm_pgoff
offsetting simply by removing the _zero suffix on the function name
and if that causes regressions, it gives us an easy way to revert.

Signed-off-by: Souptick Joarder <jrdr.linux@...il.com>
---
 drivers/auxdisplay/ht16k33.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
index 21393ec..9c0bb77 100644
--- a/drivers/auxdisplay/ht16k33.c
+++ b/drivers/auxdisplay/ht16k33.c
@@ -223,9 +223,9 @@ static int ht16k33_bl_check_fb(struct backlight_device *bl, struct fb_info *fi)
 static int ht16k33_mmap(struct fb_info *info, struct vm_area_struct *vma)
 {
 	struct ht16k33_priv *priv = info->par;
+	struct page *pages = virt_to_page(priv->fbdev.buffer);
 
-	return vm_insert_page(vma, vma->vm_start,
-			      virt_to_page(priv->fbdev.buffer));
+	return vm_map_pages_zero(vma, &pages, 1);
 }
 
 static struct fb_ops ht16k33_fb_ops = {
-- 
1.9.1