[PATCH] fbdev: update info->cmap when setting cmap from user-/kernelspace.

The fb_info struct, as defined in include/linux/fb.h, contains an element
that is supposed to hold the current color map:
  struct fb_cmap cmap;            /* Current cmap */

This cmap is currently never updated when either fb_set_cmap() or
fb_set_user_cmap() are called.  As a result, info->cmap contains the
default cmap that was set by a device driver/fbcon and a userspace
application using the FBIOGETCMAP ioctl will not always get the *currently*
used color map.

The patch fixes this by making sure the cmap is copied to info->cmap after
it is set correctly.  It moves most of the code that is responsible for
setting the cmap to fb_set_cmap() and out of fb_set_user_cmap() to avoid
code-duplication.
Signed-off-by: Michal Januszewski <spock@gentoo.org>
Cc: <linux-fbdev-devel@lists.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/video/fbcmap.c

@@ -212,7 +212,7 @@ int fb_cmap_to_user(struct fb_cmap *from, struct fb_cmap_user *to)
 
 int fb_set_cmap(struct fb_cmap *cmap, struct fb_info *info)
 {
-	int i, start;
+	int i, start, rc = 0;
 	u16 *red, *green, *blue, *transp;
 	u_int hred, hgreen, hblue, htransp = 0xffff;
 
@@ -225,8 +225,9 @@ int fb_set_cmap(struct fb_cmap *cmap, struct fb_info *info)
 	if (start < 0 || (!info->fbops->fb_setcolreg &&
 			  !info->fbops->fb_setcmap))
 		return -EINVAL;
-	if (info->fbops->fb_setcmap)
-		return info->fbops->fb_setcmap(cmap, info);
+	if (info->fbops->fb_setcmap) {
+		rc = info->fbops->fb_setcmap(cmap, info);
+	} else {
 		for (i = 0; i < cmap->len; i++) {
 			hred = *red++;
 			hgreen = *green++;
@@ -234,66 +235,41 @@ int fb_set_cmap(struct fb_cmap *cmap, struct fb_info *info)
 			if (transp)
 				htransp = *transp++;
 			if (info->fbops->fb_setcolreg(start++,
-					      hred, hgreen, hblue, htransp,
-					      info))
+						      hred, hgreen, hblue,
+						      htransp, info))
 				break;
 		}
-	return 0;
+	}
+	if (rc == 0)
+		fb_copy_cmap(cmap, &info->cmap);
+
+	return rc;
 }
 
 int fb_set_user_cmap(struct fb_cmap_user *cmap, struct fb_info *info)
 {
-	int i, start;
-	u16 __user *red, *green, *blue, *transp;
-	u_int hred, hgreen, hblue, htransp = 0xffff;
-
-	red = cmap->red;
-	green = cmap->green;
-	blue = cmap->blue;
-	transp = cmap->transp;
-	start = cmap->start;
+	int rc, size = cmap->len * sizeof(u16);
+	struct fb_cmap umap;
 
-	if (start < 0 || (!info->fbops->fb_setcolreg &&
+	if (cmap->start < 0 || (!info->fbops->fb_setcolreg &&
 			        !info->fbops->fb_setcmap))
 		return -EINVAL;
 
-	/* If we can batch, do it */
-	if (info->fbops->fb_setcmap && cmap->len > 1) {
-		struct fb_cmap umap;
-		int size = cmap->len * sizeof(u16);
-		int rc;
-
 	memset(&umap, 0, sizeof(struct fb_cmap));
-		rc = fb_alloc_cmap(&umap, cmap->len, transp != NULL);
+	rc = fb_alloc_cmap(&umap, cmap->len, cmap->transp != NULL);
 	if (rc)
 		return rc;
-		if (copy_from_user(umap.red, red, size) ||
-		    copy_from_user(umap.green, green, size) ||
-		    copy_from_user(umap.blue, blue, size) ||
-		    (transp && copy_from_user(umap.transp, transp, size))) {
-			rc = -EFAULT;
-		}
-		umap.start = start;
-		if (rc == 0)
-			rc = info->fbops->fb_setcmap(&umap, info);
+	if (copy_from_user(umap.red, cmap->red, size) ||
+	    copy_from_user(umap.green, cmap->green, size) ||
+	    copy_from_user(umap.blue, cmap->blue, size) ||
+	    (cmap->transp && copy_from_user(umap.transp, cmap->transp, size))) {
 		fb_dealloc_cmap(&umap);
-		return rc;
-	}
-
-	for (i = 0; i < cmap->len; i++, red++, blue++, green++) {
-		if (get_user(hred, red) ||
-		    get_user(hgreen, green) ||
-		    get_user(hblue, blue) ||
-		    (transp && get_user(htransp, transp)))
 		return -EFAULT;
-		if (info->fbops->fb_setcolreg(start++,
-					      hred, hgreen, hblue, htransp,
-					      info))
-			return 0;
-		if (transp)
-			transp++;
 	}
-	return 0;
+	umap.start = cmap->start;
+	rc = fb_set_cmap(&umap, info);
+	fb_dealloc_cmap(&umap);
+	return rc;
 }
 
 /**