netdev - RE: [PATCH] cxgb4vf: fix crash due to manipulating queues before registration

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Message-ID: <8A71B368A89016469F72CD08050AD334088DA49E@maui.asicdesigners.com>
Date:	Fri, 29 Oct 2010 00:36:22 -0700
From:	"Dimitrios Michailidis" <dm@...lsio.com>
To:	"David Miller" <davem@...emloft.net>,
	"Casey Leedom" <leedom@...lsio.com>
Cc:	<netdev@...r.kernel.org>
Subject: RE: [PATCH] cxgb4vf: fix crash due to manipulating queues before registration

> > Before commit "net: allocate tx queues in register_netdevice"
> > netif_tx_stop_all_queues and related functions could be used between
> > device allocation and registration but now only after registration.
> > cxgb4 has such a call before registration and crashes now.  Move it
> > after register_netdev.
> >
> > Signed-off-by: Casey Leedom <leedom@...lsio.com>
> 
> Why are you manipulating the queue at all here?
> 
> The queue state is "don't care" at this point in time,
> and has no meaning until ->open() is invoked.

The reason for the call at its initial pre register_netdev location was
an attempt to make the queues have the same state at the time of each
open.  Without it at the first open __QUEUE_STATE_XOFF is not set due to
0-initialization but at subsequent opens it is set because close stops
the queues.  I agree however that this disparity is not functionally
significant.  Further, I believe moving the call after register_netdev
is buggy as open can be called after registration and it can clash with
the queue stopping.  It seems then that these netif_tx_stop_all_queues
calls have to go now.

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