[PATCH V2] vlan priority handling in WMM

[PATCH V2] vlan priority handling in WMM

[cedric.voncken]

From: cedric voncken <cedric.voncken@acksys.fr>

If the VLAN tci is set in skb->vlan_tci use the priority field to determine the WMM priority.

V2 modifications :
	Fix indentation
	Use symbolic constant
	include the header linux/if_vlan.h

Signed-off-by: cedric Voncken <cedric.voncken@acksys.fr>
---
 net/wireless/util.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/net/wireless/util.c b/net/wireless/util.c
index 74458b7..13937db 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -10,6 +10,7 @@
 #include <net/cfg80211.h>
 #include <net/ip.h>
 #include <net/dsfield.h>
+#include <linux/if_vlan.h>
 #include "core.h"
 #include "rdev-ops.h"
 
@@ -685,6 +686,7 @@ EXPORT_SYMBOL(ieee80211_amsdu_to_8023s);
 unsigned int cfg80211_classify8021d(struct sk_buff *skb)
 {
 	unsigned int dscp;
+	unsigned char vlan_priority;
 
 	/* skb->priority values from 256->263 are magic values to
 	 * directly indicate a specific 802.1d priority.  This is used
@@ -694,6 +696,10 @@ unsigned int cfg80211_classify8021d(struct sk_buff *skb)
 	if (skb->priority >= 256 && skb->priority <= 263)
 		return skb->priority - 256;
 
+	vlan_priority = (skb->vlan_tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT;
+	if (vlan_priority > 0)
+		return vlan_priority;
+
 	switch (skb->protocol) {
 	case htons(ETH_P_IP):
 		dscp = ipv4_get_dsfield(ip_hdr(skb)) & 0xfc;
-- 
1.7.2.5

RE: [PATCH V2] vlan priority handling in WMM

[voncken]

Any comments on this patch ? 

Cedric


-----Message d'origine-----
De : linux-wireless-owner@vger.kernel.org
[mailto:linux-wireless-owner@vger.kernel.org] De la part de
cedric.voncken@acksys.fr
Envoyé : jeudi 27 juin 2013 09:52
À : johannes@sipsolutions.net
Cc : linux-wireless@vger.kernel.org; cedric voncken
Objet : [PATCH V2] vlan priority handling in WMM

From: cedric voncken <cedric.voncken@acksys.fr>

If the VLAN tci is set in skb->vlan_tci use the priority field to determine
the WMM priority.

V2 modifications :
	Fix indentation
	Use symbolic constant
	include the header linux/if_vlan.h

Signed-off-by: cedric Voncken <cedric.voncken@acksys.fr>
---
 net/wireless/util.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/net/wireless/util.c b/net/wireless/util.c index
74458b7..13937db 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -10,6 +10,7 @@
 #include <net/cfg80211.h>
 #include <net/ip.h>
 #include <net/dsfield.h>
+#include <linux/if_vlan.h>
 #include "core.h"
 #include "rdev-ops.h"
 
@@ -685,6 +686,7 @@ EXPORT_SYMBOL(ieee80211_amsdu_to_8023s);
 unsigned int cfg80211_classify8021d(struct sk_buff *skb)  {
 	unsigned int dscp;
+	unsigned char vlan_priority;
 
 	/* skb->priority values from 256->263 are magic values to
 	 * directly indicate a specific 802.1d priority.  This is used @@
-694,6 +696,10 @@ unsigned int cfg80211_classify8021d(struct sk_buff *skb)
 	if (skb->priority >= 256 && skb->priority <= 263)
 		return skb->priority - 256;
 
+	vlan_priority = (skb->vlan_tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT;
+	if (vlan_priority > 0)
+		return vlan_priority;
+
 	switch (skb->protocol) {
 	case htons(ETH_P_IP):
 		dscp = ipv4_get_dsfield(ip_hdr(skb)) & 0xfc;
--
1.7.2.5

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[PATCH V2] vlan priority handling in WMM

[voncken]

If the VLAN tci is set in skb->vlan_tci use the priority field to determine
the WMM priority.

V2 modifications :
	Fix indentation
	Use symbolic constant
	include the header linux/if_vlan.h

Signed-off-by: cedric Voncken <cedric.voncken@acksys.fr>
---
 net/wireless/util.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/net/wireless/util.c b/net/wireless/util.c index
74458b7..13937db 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -10,6 +10,7 @@
 #include <net/cfg80211.h>
 #include <net/ip.h>
 #include <net/dsfield.h>
+#include <linux/if_vlan.h>
 #include "core.h"
 #include "rdev-ops.h"
 
@@ -685,6 +686,7 @@ EXPORT_SYMBOL(ieee80211_amsdu_to_8023s);
 unsigned int cfg80211_classify8021d(struct sk_buff *skb)  {
 	unsigned int dscp;
+	unsigned char vlan_priority;
 
 	/* skb->priority values from 256->263 are magic values to
 	 * directly indicate a specific 802.1d priority.  This is used @@
-694,6 +696,10 @@ unsigned int cfg80211_classify8021d(struct sk_buff *skb)
 	if (skb->priority >= 256 && skb->priority <= 263)
 		return skb->priority - 256;
 
+	vlan_priority = (skb->vlan_tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT;
+	if (vlan_priority > 0)
+		return vlan_priority;
+
 	switch (skb->protocol) {
 	case htons(ETH_P_IP):
 		dscp = ipv4_get_dsfield(ip_hdr(skb)) & 0xfc;
--
1.7.2.5

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Re: [PATCH V2] vlan priority handling in WMM

[Johannes Berg]

On Thu, 2013-07-04 at 09:18 +0200, voncken wrote:
> If the VLAN tci is set in skb->vlan_tci use the priority field to determine
> the WMM priority.

Pinging me and resending your patch isn't going to make it more likely
that I apply it. We're in the merge window, so naturally patch
application is stalled.

johannes

RE: [PATCH V2] vlan priority handling in WMM

[voncken]

Sorry but I have some problems with my mail server, and actually, I have a lot of mail not sent. So I was not sure you received my message.

I waiting the end of merge windows

Cedric

-----Message d'origine-----
De : Johannes Berg [mailto:johannes@sipsolutions.net] 
Envoyé : jeudi 4 juillet 2013 09:47
À : voncken
Cc : linux-wireless@vger.kernel.org
Objet : Re: [PATCH V2] vlan priority handling in WMM

On Thu, 2013-07-04 at 09:18 +0200, voncken wrote:
> If the VLAN tci is set in skb->vlan_tci use the priority field to 
> determine the WMM priority.

Pinging me and resending your patch isn't going to make it more likely that I apply it. We're in the merge window, so naturally patch application is stalled.

johannes

Re: [PATCH V2] vlan priority handling in WMM

[Johannes Berg]

Subject line should have a "wireless: " (or "cfg80211: ") prefix.

> If the VLAN tci is set in skb->vlan_tci use the priority field to determine the WMM priority.
> 
> V2 modifications :
> 	Fix indentation
> 	Use symbolic constant
> 	include the header linux/if_vlan.h

This doesn't belong into the changelog, it should be after --- with the
diffstat.

johannes

Re: [PATCH V2] vlan priority handling in WMM

[Johannes Berg]

> +	vlan_priority = (skb->vlan_tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT;
> +	if (vlan_priority > 0)
> +		return vlan_priority;

Is this really correct? For once, checking vlan_priority for non-zero
seems weird since that ought to be a valid value -- is there no other
way to determine that the value is valid?

Also, this gives you a 2-bit value, while the return value should be a
3-bit value, maybe you need to shift this up by one to spread into the
correct buckets?

johannes

RE: [PATCH V2] vlan priority handling in WMM

[voncken]

> >+	vlan_priority = (skb->vlan_tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT;
> >+	if (vlan_priority > 0)
>> +		return vlan_priority;

>Is this really correct? For once, checking vlan_priority for non-zero seems weird since that ought to be a valid value -- is there no other way to determine that the value is valid?
The vlan Tag contain three bit for priority. The value 0 indicate no priority (on this case the VLAN tag contain only VID). The vlan_tci field is set to zero if the frame do not contain the vlan tag. So if we have not a vlan tag or no priority in VLAN tag the priority value is always 0. 

>Also, this gives you a 2-bit value, while the return value should be a 3-bit value, maybe you need to shift this up by one to spread into the correct buckets?
Sorry but I don't understand. The vlan_tci field it is a __u16 value (defined in include/linux/skbuff.h), the VLAN_PRIO_MASK is set to 0xE000 and VLAN_PRIO_SHIFT is set to 13 (defined in  include/linux/if_vlan.h), the vlan_priority is an unsigned char. For me the vlan_priority contain a 3-bit value (0xE000 >>13 = 0x0003), why 2 ?

If you are agree with me, I'll resend a V3 patch with a correct subject.

Cedric

>johannes

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Re: [PATCH V2] vlan priority handling in WMM

[Johannes Berg]

On Fri, 2013-07-05 at 16:39 +0200, voncken wrote:
> > >+	vlan_priority = (skb->vlan_tci & VLAN_PRIO_MASK) >>
> VLAN_PRIO_SHIFT;
> > >+	if (vlan_priority > 0)
> >> +		return vlan_priority;
> 
> > Is this really correct? For once, checking vlan_priority for
> non-zero seems
> > weird since that ought to be a valid value -- is there no other way
> to
> > determine that the value is valid?

> The vlan Tag contain three bit for priority. The value 0 indicate no
> priority (on this case the VLAN tag contain only VID). The vlan_tci
> field is set to zero if the frame do not contain the vlan tag. So if
> we have not a vlan tag or no priority in VLAN tag the priority value
> is always 0. 

Yes but don't we know that the vlan_tci field is valid?

I don't think you're correct in that 0 means "no priority present", it
actually means "best effort" as far as I can tell. Ignoring the VLAN tag
when the field is 0 would mean we could use a higher priority from the
contents of the frame, which would not be desired?

> >Also, this gives you a 2-bit value, while the return value should be
> a 3-bit value, maybe you need to shift this up by one to spread into
> the correct buckets?
> Sorry but I don't understand. The vlan_tci field it is a __u16 value
> (defined in include/linux/skbuff.h), the VLAN_PRIO_MASK is set to
> 0xE000 and VLAN_PRIO_SHIFT is set to 13 (defined in
> include/linux/if_vlan.h), the vlan_priority is an unsigned char. For
> me the vlan_priority contain a 3-bit value (0xE000 >>13 = 0x0003), why
> 2 ?

Umm? No? Think again about what hweight(0x0003) is.

johannes

RE: [PATCH V2] vlan priority handling in WMM

[voncken]

> > The vlan Tag contain three bit for priority. The value 0 indicate no 
> > priority (on this case the VLAN tag contain only VID). The vlan_tci 
> > field is set to zero if the frame do not contain the vlan tag. So if 
> > we have not a vlan tag or no priority in VLAN tag the priority value 
> > is always 0.

> Yes but don't we know that the vlan_tci field is valid?

> I don't think you're correct in that 0 means "no priority present", it actually means "best effort" as far as I can tell. Ignoring the VLAN tag when the field is 0 would mean we could use a higher priority from the contents of the frame, which would not be desired?

I can add a test with the macro vlan_tx_tag_present() to verify if the vlan_tci field is valid. 
I test the value 0 to skip the VLAN priority and use the dscp priority in this case. The priority 0 in VLAN tag is often use to turn off the QOS, because not bit is allowed for it.
For me is it correct. Nevertheless, if you prefer, I can test only the vlan_tci validity and in this case always use the VLAN priority.

> > Sorry but I don't understand. The vlan_tci field it is a __u16 value 
> > (defined in include/linux/skbuff.h), the VLAN_PRIO_MASK is set to
> > 0xE000 and VLAN_PRIO_SHIFT is set to 13 (defined in 
> > include/linux/if_vlan.h), the vlan_priority is an unsigned char. For 
> > me the vlan_priority contain a 3-bit value (0xE000 >>13 = 0x0003), why
> > 2 ?

> Umm? No? Think again about what hweight(0x0003) is.

Sorry I made a mistake  0xE000 >>13 = 0x0007 and not 0x0003, and 7 is a 3 bits value.

Cedric

Re: [PATCH V2] vlan priority handling in WMM

[Johannes Berg]

On Mon, 2013-07-08 at 12:39 +0200, voncken wrote:
> > > The vlan Tag contain three bit for priority. The value 0 indicate
> no 
> > > priority (on this case the VLAN tag contain only VID). The
> vlan_tci 
> > > field is set to zero if the frame do not contain the vlan tag. So
> if 
> > > we have not a vlan tag or no priority in VLAN tag the priority
> value 
> > > is always 0.
> 
> > Yes but don't we know that the vlan_tci field is valid?
> 
> > I don't think you're correct in that 0 means "no priority present",
> it actually means "best effort" as far as I can tell. Ignoring the
> VLAN tag when the field is 0 would mean we could use a higher priority
> from the contents of the frame, which would not be desired?
> 
> I can add a test with the macro vlan_tx_tag_present() to verify if the
> vlan_tci field is valid. 
> I test the value 0 to skip the VLAN priority and use the dscp priority
> in this case. The priority 0 in VLAN tag is often use to turn off the
> QOS, because not bit is allowed for it.

What do you mean by "is often used"? I don't see how that would be the
case? Are you saying routers commonly ignore the VLAN priority value if
it's 0? That would seem odd?

> For me is it correct. Nevertheless, if you prefer, I can test only the
> vlan_tci validity and in this case always use the VLAN priority.

I don't know! Since you don't seem to really know either, we should ask
somebody who knows, I think. Maybe you should Cc netdev with this
question on the patch or so?

> Sorry I made a mistake  0xE000 >>13 = 0x0007 and not 0x0003, and 7 is
> a 3 bits value.

Ah yes, I made the same mistake, sorry.

johannes