[PATCH] framebuffer: cmap-setting return values

A set of 3 small bugfixes, all of which are related to bogus return values
of fb colormap-setting functions.

First, fb_alloc_cmap returns -1 if memory allocation fails. This is a hard
condition to reproduce since you'd have to be really low on memory, but from
studying the contexts in which it is called, I think this function should be
returning a negative errno, and the -1 will be seen as an EPERM. Switching it
to -ENOMEM makes sense.

Second, the store_cmap function which is called for writes to
/sys/class/graphics/fb0/color_map returns 0 for success, but it should be
returning the count of bytes written since its return value ends up in
userspace as the result of the write() syscall.

Third, radeonfb returns 1 instead of a negative errno when FBIOPUTCMAP is
called with an oversized colormap.  This is seen in userspace as a return
value of 1 from the ioctl() syscall with errno left unchanged.  A more
useful return value would be -EINVAL.

Signed-off-by: Alan Curry <pacman@TheWorld.com>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/video/fbsysfs.c

@@ -348,7 +348,7 @@ static ssize_t store_cmap(struct class_device *class_device, const char *buf,
 		fb_copy_cmap(&umap, &fb_info->cmap);
 		fb_dealloc_cmap(&umap);
 
-		return rc;
+		return rc ?: count;
 	}
 	for (i = 0; i < length; i++) {
 		u16 red, blue, green, tsp;
@@ -367,7 +367,7 @@ static ssize_t store_cmap(struct class_device *class_device, const char *buf,
 		if (transp)
 			fb_info->cmap.transp[i] = tsp;
 	}
-	return 0;
+	return count;
 }
 
 static ssize_t show_cmap(struct class_device *class_device, char *buf)