linux-kernel - [VIDEO] vfb: only enable if explicitly requested when compiled in

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Message-Id: <200806011454.23123.elendil@planet.nl>
Date:	Sun, 1 Jun 2008 14:54:22 +0200
From:	Frans Pop <elendil@...net.nl>
To:	linux-fbdev-devel@...ts.sourceforge.net
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Antonino A. Daplas" <adaplas@...il.com>
Subject: [VIDEO] vfb: only enable if explicitly requested when compiled in

From: Frans Pop <elendil@...net.nl>

The Kconfig help for the vfb driver says:
   Do NOT enable it for normal systems! To protect the innocent, it
   has to be enabled explicitly at boot time using the kernel option
   `video=vfb:'.

This change lets the code match the description.

Support for vfb:disable is kept for backwards compatibility; vfb:off
works because it is tested at a higher level.

Signed-off-by: Frans Pop <elendil@...net.nl>
CC: Antonino A. Daplas <adaplas@...il.com>
CC: Andrew Morton <akpm@...ux-foundation.org>

---
Note: any undefined option (e.g. vfb:enable) will also enable this driver.

The relevant code has been unchanged since before the migration to
git (2.6.12).

This patch fixes bugzilla #9310 and was the root cause behind
http://lkml.org/lkml/2008/5/31/220.

My confusion stemmed from the fact that I was still assuming that the
Kconfig help would be correct (even though Antonino had already
determined it was not: http://lkml.org/lkml/2007/10/14/25, but somehow
my brain never parsed that).

diff --git a/drivers/video/vfb.c b/drivers/video/vfb.c
index 072638a..51e935f 100644
--- a/drivers/video/vfb.c
+++ b/drivers/video/vfb.c
@@ -443,19 +443,29 @@ static int vfb_mmap(struct fb_info *info,
 }

 #ifndef MODULE
+/*
+ * The virtual framebuffer driver is only enabled if explicitly
+ * requested by passing 'video=vfb:' (or any actual options).
+ */
 static int __init vfb_setup(char *options)
 {
 	char *this_opt;

-	vfb_enable = 1;
+	vfb_enable = 0;

-	if (!options || !*options)
+	if (!options)
+		return 1;
+
+	vfb_enable = 1;
+
+	if (!*options)
 		return 1;

 	while ((this_opt = strsep(&options, ",")) != NULL) {
 		if (!*this_opt)
 			continue;
-		if (!strncmp(this_opt, "disable", 7))
+		/* Test disable for backwards compatibility */
+		if (!strcmp(this_opt, "disable"))
 			vfb_enable = 0;
 	}
 	return 1;
--
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