Re: Signed bit field; int have_hotplug_status_watch:1

Re: Signed bit field; int have_hotplug_status_watch:1

[Ian Campbell]

On Sun, 2011-04-03 at 22:32 +0100, Dr. David Alan Gilbert wrote:
> Hi Ian,
>    I've been going through some sparse scans of the kernel and
> it threw up:
> 
>   CHECK   drivers/net/xen-netback/xenbus.c
> drivers/net/xen-netback/xenbus.c:29:40: error: dubious one-bit signed bitfield
> 
>         int have_hotplug_status_watch:1;
> 
> from your patch f942dc2552b8bfdee607be867b12a8971bb9cd85 
> 
> It does look like that should be an unsigned (given it's assigned
> 0 and 1)

I agree.

8<----------------------------------

>From 38fdb7199a0c3c5eb18ec27d2380e21116c97e29 Mon Sep 17 00:00:00 2001
From: Ian Campbell <ian.campbell@citrix.com>
Date: Mon, 4 Apr 2011 09:18:35 +0100
Subject: [PATCH] xen: netback: use unsigned type for one-bit bitfield.

Fixes error from sparse:
  CHECK   drivers/net/xen-netback/xenbus.c
drivers/net/xen-netback/xenbus.c:29:40: error: dubious one-bit signed bitfield

        int have_hotplug_status_watch:1;

Reported-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: netdev@vger.kernel.org
Cc: xen-devel@lists.xensource.com
---
 drivers/net/xen-netback/xenbus.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 22b8c35..1ce729d 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -26,7 +26,7 @@ struct backend_info {
 	struct xenvif *vif;
 	enum xenbus_state frontend_state;
 	struct xenbus_watch hotplug_status_watch;
-	int have_hotplug_status_watch:1;
+	u8 have_hotplug_status_watch:1;
 };
 
 static int connect_rings(struct backend_info *);
-- 
1.7.2.5

Re: Signed bit field; int have_hotplug_status_watch:1

[David Miller]

From: Ian Campbell <Ian.Campbell@eu.citrix.com>
Date: Mon, 4 Apr 2011 09:26:24 +0100

> Subject: [PATCH] xen: netback: use unsigned type for one-bit bitfield.
> 
> Fixes error from sparse:
>   CHECK   drivers/net/xen-netback/xenbus.c
> drivers/net/xen-netback/xenbus.c:29:40: error: dubious one-bit signed bitfield
> 
>         int have_hotplug_status_watch:1;
> 
> Reported-by: Dr. David Alan Gilbert <linux@treblig.org>
> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>

Applied to net-next-2.6, thanks.