[PATCH] hdlc: fix compile problem

[PATCH] hdlc: fix compile problem

[Stephen Hemminger]

Fix build problem with hdlc driver. hdlc_null_ops was being referenced
before it was defined!

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>

--- a/drivers/net/wan/hdlc.c	2009-01-07 14:08:43.510247589 -0800
+++ b/drivers/net/wan/hdlc.c	2009-01-07 14:09:39.093495837 -0800
@@ -40,6 +40,8 @@
 
 static const char* version = "HDLC support module revision 1.22";
 
+static const struct header_ops hdlc_null_ops;
+
 #undef DEBUG_LINK
 
 static struct hdlc_proto *first_proto;
@@ -218,8 +220,6 @@ int hdlc_ioctl(struct net_device *dev, s
 	return -EINVAL;
 }
 
-static const struct header_ops hdlc_null_ops;
-
 static void hdlc_setup_dev(struct net_device *dev)
 {
 	/* Re-init all variables changed by HDLC protocol drivers,

Re: [PATCH] hdlc: fix compile problem

[Krzysztof Halasa]

Stephen Hemminger <shemminger@vyatta.com> writes:

> Fix build problem with hdlc driver. hdlc_null_ops was being referenced
> before it was defined!

:-)

Unfortunately I can't see it, which tree is it?


In David's and Linus' trees it appears twice, it seem to be entirely
correct and btw you are the author :-)
... and it compiled here 100 times or so :-)

static const struct header_ops hdlc_null_ops;
                               ^^^^^^^^^^^^^
static void hdlc_setup_dev(struct net_device *dev)
{
        /* Re-init all variables changed by HDLC protocol drivers,
         * including ether_setup() called from hdlc_raw_eth.c.
         */
        dev->get_stats           = hdlc_get_stats;
        dev->flags               = IFF_POINTOPOINT | IFF_NOARP;
        dev->mtu                 = HDLC_MAX_MTU;
        dev->type                = ARPHRD_RAWHDLC;
        dev->hard_header_len     = 16;
        dev->addr_len            = 0;
        dev->header_ops          = &hdlc_null_ops;
                                  ^^^^^^^^^^^^^^^^
        dev->change_mtu          = hdlc_change_mtu;
}
-- 
Krzysztof Halasa

Re: [PATCH] hdlc: fix compile problem

[Stephen Hemminger]

On Thu, 08 Jan 2009 00:21:03 +0100
Krzysztof Halasa <khc@pm.waw.pl> wrote:

> Stephen Hemminger <shemminger@vyatta.com> writes:
> 
> > Fix build problem with hdlc driver. hdlc_null_ops was being referenced
> > before it was defined!
> 
> :-)
> 
> Unfortunately I can't see it, which tree is it?
> 
> 
> In David's and Linus' trees it appears twice, it seem to be entirely
> correct and btw you are the author :-)
> ... and it compiled here 100 times or so :-)
> 
> static const struct header_ops hdlc_null_ops;
>                                ^^^^^^^^^^^^^
> static void hdlc_setup_dev(struct net_device *dev)
> {
>         /* Re-init all variables changed by HDLC protocol drivers,
>          * including ether_setup() called from hdlc_raw_eth.c.
>          */
>         dev->get_stats           = hdlc_get_stats;
>         dev->flags               = IFF_POINTOPOINT | IFF_NOARP;
>         dev->mtu                 = HDLC_MAX_MTU;
>         dev->type                = ARPHRD_RAWHDLC;
>         dev->hard_header_len     = 16;
>         dev->addr_len            = 0;
>         dev->header_ops          = &hdlc_null_ops;
>                                   ^^^^^^^^^^^^^^^^
>         dev->change_mtu          = hdlc_change_mtu;
> }

It was introduced (by me) in previous patch. Since that isn't applied yet,
I'll go back and fix.

Re: [PATCH] hdlc: fix compile problem

[Krzysztof Halasa]

Stephen Hemminger <shemminger@vyatta.com> writes:

> It was introduced (by me) in previous patch. Since that isn't applied yet,
> I'll go back and fix.

I can see it now, I must have missed it because of the "synclink"
subject.

@@ -106,7 +98,7 @@ static int hdlc_device_event(struct noti
        if (dev_net(dev) != &init_net)
                return NOTIFY_DONE;
 
-       if (dev->get_stats != hdlc_get_stats)
+       if (dev->header_ops != &hdlc_null_ops)
                return NOTIFY_DONE; /* not an HDLC device */

This won't work because hdlc_null_ops may be substituted by
cisco_header_ops or ppp_header_ops. Current test works for now but is
wrong, too, at least for wanxl driver (it tries to use its
get_stats()).

Perhaps some
+       if (dev->header_ops->something != &something)
would do? Alternatively we can return to hdlc_carrier_on|off() and
hdlc_device_event() won't be needed.

Essentially, it's a bit hard to check if the device is one of ours if
we are the middle layer.


There are two layers here:
- hardware drivers (10+)
- protocol drivers (5 - hdlc* files)

Protocol drivers want to define things like:
- dev->header_ops (no problem)
- dev->change_mtu (perhaps)
- dev->hard_start_xmit

Hardware drivers need to define the rest of NDO.

Hmm, not much, only hard_start_xmit() is really problematic. I think
we need a trampoline: hw driver will define the NDO and set
hard_start_xmit and possibly change_mtu to (exported by hdlc.c)
hdlc_xmit (hdlc_change_mtu), and hdlc_start_xmit will just call
protocol's xmit().
We could also use it for the test in hdlc_device_event:
	if (dev->netdev_ops->start_hard_xmit != hdlc_xmit)

If we could then get rid of this special xmit() and do all header and
TX preparations in hard_header(), it would be even better (cleaner)
though IIRC it requires some changes to Ethernet(?) code.


The changes have to be applied to the 4 synclink drivers and to most
.c files in drivers/net/wan simultaneously, perhaps it's more practical
if I do it?
-- 
Krzysztof Halasa

Re: [PATCH] hdlc: fix compile problem

[Stephen Hemminger]

On Thu, 08 Jan 2009 02:00:00 +0100
Krzysztof Halasa <khc@pm.waw.pl> wrote:

> Stephen Hemminger <shemminger@vyatta.com> writes:
> 
> > It was introduced (by me) in previous patch. Since that isn't applied yet,
> > I'll go back and fix.
> 
> I can see it now, I must have missed it because of the "synclink"
> subject.
> 
> @@ -106,7 +98,7 @@ static int hdlc_device_event(struct noti
>         if (dev_net(dev) != &init_net)
>                 return NOTIFY_DONE;
>  
> -       if (dev->get_stats != hdlc_get_stats)
> +       if (dev->header_ops != &hdlc_null_ops)
>                 return NOTIFY_DONE; /* not an HDLC device */
> 
> This won't work because hdlc_null_ops may be substituted by
> cisco_header_ops or ppp_header_ops. Current test works for now but is
> wrong, too, at least for wanxl driver (it tries to use its
> get_stats()).
> 
> Perhaps some
> +       if (dev->header_ops->something != &something)
> would do? Alternatively we can return to hdlc_carrier_on|off() and
> hdlc_device_event() won't be needed.
> 
> Essentially, it's a bit hard to check if the device is one of ours if
> we are the middle layer.
> 
> 
> There are two layers here:
> - hardware drivers (10+)
> - protocol drivers (5 - hdlc* files)
> 
> Protocol drivers want to define things like:
> - dev->header_ops (no problem)
> - dev->change_mtu (perhaps)
> - dev->hard_start_xmit
> 
> Hardware drivers need to define the rest of NDO.
> 
> Hmm, not much, only hard_start_xmit() is really problematic. I think
> we need a trampoline: hw driver will define the NDO and set
> hard_start_xmit and possibly change_mtu to (exported by hdlc.c)
> hdlc_xmit (hdlc_change_mtu), and hdlc_start_xmit will just call
> protocol's xmit().
> We could also use it for the test in hdlc_device_event:
> 	if (dev->netdev_ops->start_hard_xmit != hdlc_xmit)
> 
> If we could then get rid of this special xmit() and do all header and
> TX preparations in hard_header(), it would be even better (cleaner)
> though IIRC it requires some changes to Ethernet(?) code.
> 
> 
> The changes have to be applied to the 4 synclink drivers and to most
> .c files in drivers/net/wan simultaneously, perhaps it's more practical
> if I do it?

Alternatively, how about this:

--- a/drivers/net/wan/hdlc.c	2009-01-07 17:04:52.002497019 -0800
+++ b/drivers/net/wan/hdlc.c	2009-01-07 17:07:02.874497531 -0800
@@ -40,8 +40,6 @@
 
 static const char* version = "HDLC support module revision 1.22";
 
-static const struct header_ops hdlc_null_ops;
-
 #undef DEBUG_LINK
 
 static struct hdlc_proto *first_proto;
@@ -100,7 +98,7 @@ static int hdlc_device_event(struct noti
 	if (dev_net(dev) != &init_net)
 		return NOTIFY_DONE;
 
-	if (dev->header_ops != &hdlc_null_ops)
+	if (dev->priv_flags & IFF_WAN_HDLC)
 		return NOTIFY_DONE; /* not an HDLC device */
 
 	if (event != NETDEV_CHANGE)
@@ -220,12 +218,15 @@ int hdlc_ioctl(struct net_device *dev, s
 	return -EINVAL;
 }
 
+static const struct header_ops hdlc_null_ops;
+
 static void hdlc_setup_dev(struct net_device *dev)
 {
 	/* Re-init all variables changed by HDLC protocol drivers,
 	 * including ether_setup() called from hdlc_raw_eth.c.
 	 */
 	dev->flags		 = IFF_POINTOPOINT | IFF_NOARP;
+	dev->priv_flags		 = IFF_WAN_HDLC;
 	dev->mtu		 = HDLC_MAX_MTU;
 	dev->type		 = ARPHRD_RAWHDLC;
 	dev->hard_header_len	 = 16;
--- a/include/linux/if.h	2009-01-07 17:03:04.397497564 -0800
+++ b/include/linux/if.h	2009-01-07 17:07:42.499169960 -0800
@@ -66,6 +66,7 @@
 #define IFF_SLAVE_NEEDARP 0x40		/* need ARPs for validation	*/
 #define IFF_ISATAP	0x80		/* ISATAP interface (RFC4214)	*/
 #define IFF_MASTER_ARPMON 0x100		/* bonding master, ARP mon in use */
+#define IFF_WAN_HDLC	0x200		/* WAN HDLC device              */
 
 #define IF_GET_IFACE	0x0001		/* for querying only */
 #define IF_GET_PROTO	0x0002

Re: [PATCH] hdlc: fix compile problem

[Krzysztof Halasa]

Stephen Hemminger <shemminger@vyatta.com> writes:

> Alternatively, how about this:
>
> --- a/drivers/net/wan/hdlc.c	2009-01-07 17:04:52.002497019 -0800
> +++ b/drivers/net/wan/hdlc.c	2009-01-07 17:07:02.874497531 -0800
> @@ -40,8 +40,6 @@
>  
>  static const char* version = "HDLC support module revision 1.22";
>  
> -static const struct header_ops hdlc_null_ops;
> -
>  #undef DEBUG_LINK
>  
>  static struct hdlc_proto *first_proto;
> @@ -100,7 +98,7 @@ static int hdlc_device_event(struct noti
>  	if (dev_net(dev) != &init_net)
>  		return NOTIFY_DONE;
>  
> -	if (dev->header_ops != &hdlc_null_ops)
> +	if (dev->priv_flags & IFF_WAN_HDLC)
>  		return NOTIFY_DONE; /* not an HDLC device */
>  
>  	if (event != NETDEV_CHANGE)

"dev->netdev_ops->start_hard_xmit != hdlc_xmit" is a dirty hack.
IFF_WAN_HDLC is much cleaner though it's an additional bit consumed.
Sure, I like it.
-- 
Krzysztof Halasa

Re: [PATCH] hdlc: fix compile problem

[David Miller]

From: Krzysztof Halasa <khc@pm.waw.pl>
Date: Thu, 08 Jan 2009 02:26:31 +0100

> "dev->netdev_ops->start_hard_xmit != hdlc_xmit" is a dirty hack.
> IFF_WAN_HDLC is much cleaner though it's an additional bit consumed.
> Sure, I like it.

Ok, Stephen please formally resubmit this final version with
full commit message etc..

Thanks.

Re: [PATCH] hdlc: fix compile problem

[Krzysztof Halasa]

>> The changes have to be applied to the 4 synclink drivers and to most
>> .c files in drivers/net/wan simultaneously, perhaps it's more practical
>> if I do it?

Ok, I will do.
-- 
Krzysztof Halasa