[PATCH take2] softmac: remove netif_tx_disable when scanning

[PATCH take2] softmac: remove netif_tx_disable when scanning

[Larry Finger]

From: Michael Buesch <mb-fseUSCV1ubazQB+pC5nmwQ@public.gmane.org>

In the scan section of ieee80211softmac, network transmits are disabled.
When SoftMAC re-enables transmits, it may override the wishes of a driver
that may have very good reasons for disabling transmits. At least one failure
in bcm43xx can be traced to this problem. In addition, several unexplained
problems may arise from the unexpected enabling of transmits. Note that
making this change introduces a new bug that would allow transmits for the
current session to be transmitted on the wrong channel; however, the new bug
is much less severe than the one being fixed, as the new one only leads to
a few retransmits, whereas the old one can bring the interface down.

A fix that will not introduce new bugs is being investigated; however, the current,
more serious one should be fixed now.

Signed-off-by: Michael Buesch <mb-fseUSCV1ubazQB+pC5nmwQ@public.gmane.org>
Signed-off-by: Larry Finger <Larry.Finger-tQ5ms3gMjBLk1uMJSBkQmQ@public.gmane.org>
---

John,

I assume you have seen the discussion on this matter in the netdev mailing list.
I agree with Michael that this patch should be applied despite the intoduction
of a new bug. Please apply this to wireless-2.6 and push it upstream for inclusion
in 2.6.19, if possible. I will be submitting it to 2.6.18.Y.

Larry


Index: linux-2.6.19-rc5/net/ieee80211/softmac/ieee80211softmac_scan.c
===================================================================
--- linux-2.6.19-rc5.orig/net/ieee80211/softmac/ieee80211softmac_scan.c
+++ linux-2.6.19-rc5/net/ieee80211/softmac/ieee80211softmac_scan.c
@@ -47,7 +47,6 @@ ieee80211softmac_start_scan(struct ieee8
 	sm->scanning = 1;
 	spin_unlock_irqrestore(&sm->lock, flags);
 
-	netif_tx_disable(sm->ieee->dev);
 	ret = sm->start_scan(sm->dev);
 	if (ret) {
 		spin_lock_irqsave(&sm->lock, flags);
@@ -248,7 +246,6 @@ void ieee80211softmac_scan_finished(stru
 		if (net)
 			sm->set_channel(sm->dev, net->channel);
 	}
-	netif_wake_queue(sm->ieee->dev);
 	ieee80211softmac_call_events(sm, IEEE80211SOFTMAC_EVENT_SCAN_FINISHED, NULL);
 }
 EXPORT_SYMBOL_GPL(ieee80211softmac_scan_finished);

---

Re: [PATCH take2] softmac: remove netif_tx_disable when scanning

[Michael Buesch]

On Monday 27 November 2006 21:37, Larry Finger wrote:
> From: Michael Buesch <mb-fseUSCV1ubazQB+pC5nmwQ@public.gmane.org>
> 
> In the scan section of ieee80211softmac, network transmits are disabled.
> When SoftMAC re-enables transmits, it may override the wishes of a driver
> that may have very good reasons for disabling transmits. At least one failure
> in bcm43xx can be traced to this problem. In addition, several unexplained
> problems may arise from the unexpected enabling of transmits.


> Note that 
> making this change introduces a new bug that would allow transmits for the
> current session to be transmitted on the wrong channel;

Nono, please don't confuse that.
It does not _indruduce_ a new bug. The bug is already there. It's only less
likely to trigger without this bugfix patch.

> however, the new bug 
> is much less severe than the one being fixed, as the new one only leads to
> a few retransmits, whereas the old one can bring the interface down.

Yeah, that too.

-- 
Greetings Michael.