netdev - Re: [PATCH] mac80211: Fix TX after monitor interface is converted to managed

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Message-ID: <20071004085440.008216c6@freepuppy.rosehill>
Date:	Thu, 4 Oct 2007 08:54:40 -0700
From:	Stephen Hemminger <shemminger@...ux-foundation.org>
To:	Daniel Drake <dsd@...too.org>
Cc:	linville@...driver.com, johannes@...solutions.net,
	netdev@...r.kernel.org, linux-wireless@...r.kernel.org
Subject: Re: [PATCH] mac80211: Fix TX after monitor interface is converted
 to managed

On Thu,  4 Oct 2007 12:33:43 +0100 (BST)
Daniel Drake <dsd@...too.org> wrote:

> This sequence of events causes loss of connectivity:
> 
> <plug in>
> <associate as normal in managed mode>
> ifconfig eth7 down
> iwconfig eth7 mode monitor
> ifconfig eth7 up
> ifconfig eth7 down
> iwconfig eth7 mode managed
> <associate as normal>
> 
> At this point you are associated but TX does not work. This is because
> the eth7 hard_start_xmit is still ieee80211_monitor_start_xmit.
> 
> Fix this by unsetting the hard_start_xmit handler in ieee80211_if_reinit. It
> will then be reinitialised to the default (ieee80211_subif_start_xmit) in
> ieee80211_if_set_type.
> 
> Signed-off-by: Daniel Drake <dsd@...too.org>

Playing with the function pointer is a awkward way to do this.  Shouldn't
the state management flags be used instead (dormant, running, stop/wake)...
I am concerned about races and dereferencing the NULL ptr.

-- 
Stephen Hemminger <shemminger@...ux-foundation.org>
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