From mboxrd@z Thu Jan  1 00:00:00 1970
From: Roland Dreier <rdreier@cisco.com>
Subject: Re: Printing the driver name as part of the netdev watchdog message
Date: Mon, 07 Jul 2008 15:45:38 -0700
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Cc: shemminger@vyatta.com, arjan@infradead.org, netdev@vger.kernel.org
To: David Miller <davem@davemloft.net>
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 > > For consistency each call through ethtool_ops should
 > > be holding rtnl mutex. And since dev_watchdog is a timer routine,
 > > it is not safe to acquire a mutex there.
 > 
 > I think "get driver info", which does nothing but copy strings out of
 > the driver software state, is a safe exception to these strict locking
 > rules.

it seems that's not universally the case, eg get_drvinfo() in
drivers/net/cxgb3/cxgb3_main.c does

	t3_get_fw_version(adapter, &fw_vers);
	t3_get_tp_version(adapter, &tp_vers);

and from reading further in the code it's not obvious that this is safe
to do without serialization (it calls into t3_read_flash(), which does a
typical "write address reg, read data reg" sequence to access flash,
without any locking).

 - R.