netdev - Re: [RFC PATCH] smsc911x: protect INT_EN read-modify-write with spinlock

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Date:	Mon, 26 Jan 2009 09:56:55 +0000
From:	Steve.Glendinning@...c.com
To:	David Miller <davem@...emloft.net>
Cc:	ian.saturley@...c.com, netdev@...r.kernel.org
Subject: Re: [RFC PATCH] smsc911x: protect INT_EN read-modify-write with spinlock

David Miller <davem@...emloft.net> wrote on 26/01/2009 01:47:36:

> From: Steve Glendinning <steve.glendinning@...c.com>
> Date: Tue, 20 Jan 2009 14:01:54 +0000
> 
> > This patch adds a new spinlock to protect read-modify-writes to the
> > INT_EN register when enabling and disabling interrupt sources.
> > 
> > I haven't actually seen any devices lock up, but I think there's a
> > possibility and I'd like to eliminate it.
> > 
> > Should I add this new spinlock, or should I extend the mac_lock
> > to also cover these sections (renaming it to simply "lock")?
> > 
> > Signed-off-by: Steve Glendinning <steve.glendinning@...c.com>
> 
> If you didn't have all of these RX multicast workaround
> cases, things would be much easier.
> 
> The POLL and normal interrupt paths are already completely atomic for
> you already.  And since POLL cannot happen until open() completes
> that path would be safe too.
> 

Thanks for looking this over David.

It looks like I can do away with the need for this if I leave RXSTOP_INT
permanently enabled and use a flag in pdata to indicate whether the ISR
should do a multicast filter update.  Does this sound reasonable?

Please drop this patch.

Steve
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