[PATCH 04/13] vt: Calculate font-buffer size with vc_font_size()

[Thomas Zimmermann]

In fbcon, fbcon_resize() computes the size of the font buffer from the
values stored in vc_font. Move these calculations to the dedicated helpers
vc_font_pitch() and vc_font_size().

Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
---
 drivers/video/fbdev/core/fbcon.c |  9 ++-------
 include/linux/console_struct.h   | 28 ++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 5467b37b1441..96cf890aa0c9 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -2042,7 +2042,6 @@ static void updatescrollmode(struct fbcon_display *p,
 }
 
 #define PITCH(w) (((w) + 7) >> 3)
-#define CALC_FONTSZ(h, p, c) ((h) * (p) * (c)) /* size = height * pitch * charcount */
 
 static int fbcon_resize(struct vc_data *vc, unsigned int width,
 			unsigned int height, bool from_user)
@@ -2054,8 +2053,7 @@ static int fbcon_resize(struct vc_data *vc, unsigned int width,
 	int x_diff, y_diff, virt_w, virt_h, virt_fw, virt_fh;
 
 	if (p->userfont && FNTSIZE(vc->vc_font.data)) {
-		int size;
-		int pitch = PITCH(vc->vc_font.width);
+		unsigned int size = vc_font_size(&vc->vc_font);
 
 		/*
 		 * If user font, ensure that a possible change to user font
@@ -2064,10 +2062,7 @@ static int fbcon_resize(struct vc_data *vc, unsigned int width,
 		 * charcount can change and cannot be used to determine the
 		 * font data allocated size.
 		 */
-		if (pitch <= 0)
-			return -EINVAL;
-		size = CALC_FONTSZ(vc->vc_font.height, pitch, vc->vc_font.charcount);
-		if (size > FNTSIZE(vc->vc_font.data))
+		if (!size || size > FNTSIZE(vc->vc_font.data))
 			return -EINVAL;
 	}
 
diff --git a/include/linux/console_struct.h b/include/linux/console_struct.h
index 7fdcae6ed49c..fbb5dd5f6761 100644
--- a/include/linux/console_struct.h
+++ b/include/linux/console_struct.h
@@ -83,6 +83,34 @@ struct vc_font {
 	const unsigned char *data;
 };
 
+/**
+ * vc_font_pitch - Calculates the number of bytes between two adjacent scanlines
+ * @font: The VC font
+ *
+ * Returns:
+ * The number of bytes between two adjacent scanlines in the font data
+ */
+static inline unsigned int vc_font_pitch(const struct vc_font *font)
+{
+	return DIV_ROUND_UP(font->width, 8);
+}
+
+/**
+ * vc_font_size - Calculates the size of the font data in bytes
+ * @font: The VC font
+ *
+ * vc_font_size() calculates the number of bytes of font data in the
+ * font specified by @font. The function calculates the size from the
+ * font parameters.
+ *
+ * Returns:
+ * The size of the font data in bytes.
+ */
+static inline unsigned int vc_font_size(const struct vc_font *font)
+{
+	return font->height * vc_font_pitch(font) * font->charcount;
+}
+
 /*
  * Example: vc_data of a console that was scrolled 3 lines down.
  *
-- 
2.52.0