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From: Roland Dreier <rdreier@cisco.com>
To: David Miller <davem@davemloft.net>
Cc: shemminger@vyatta.com, arjan@infradead.org, netdev@vger.kernel.org
Subject: Re: Printing the driver name as part of the netdev watchdog message
Date: Mon, 07 Jul 2008 15:45:38 -0700	[thread overview]
Message-ID: <adafxqlxqi5.fsf@cisco.com> (raw)
In-Reply-To: <20080706.182243.65603166.davem@davemloft.net> (David Miller's message of "Sun, 06 Jul 2008 18:22:43 -0700 (PDT)")

 > > 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.

  parent reply	other threads:[~2008-07-07 22:45 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-07-06 20:08 Printing the driver name as part of the netdev watchdog message Arjan van de Ven
2008-07-06 22:53 ` David Miller
2008-07-06 23:56   ` Arjan van de Ven
2008-07-07  1:51     ` Wang Chen
2008-07-07  3:59       ` David Miller
2008-07-07  4:34         ` Arjan van de Ven
2008-07-07  4:49           ` David Miller
2008-07-07  4:57             ` Arjan van de Ven
2008-07-07  6:44               ` David Miller
2008-07-07 15:23                 ` Arjan van de Ven
2008-07-07  1:08   ` Stephen Hemminger
2008-07-07  1:22     ` David Miller
2008-07-07  1:53       ` Jeff Garzik
2008-07-07 17:05         ` Stephen Hemminger
2008-07-07 22:45       ` Roland Dreier [this message]
2008-07-07 22:57         ` David Miller
2008-07-07 23:14           ` Roland Dreier
2008-07-07 23:44             ` Stephen Hemminger
2008-07-08  0:10               ` Arjan van de Ven
2008-07-08 19:13             ` Steve Wise
2008-07-08 21:31               ` David Miller
2008-07-08 21:47                 ` Arjan van de Ven
2008-07-08 21:57                   ` David Miller
2008-07-08 23:48                     ` Arjan van de Ven
2008-07-08 23:53                       ` David Miller
2008-07-09  0:17                         ` Arjan van de Ven
2008-07-09  1:44                         ` Arjan van de Ven
2008-07-09  3:16                           ` Stephen Hemminger
2008-07-09 17:20                             ` Joe Perches
2008-07-09 17:56                               ` Arjan van de Ven
2008-07-09 18:20                                 ` Joe Perches
2008-07-09 18:50                                   ` Arjan van de Ven
2008-07-09 18:28                                 ` Ben Hutchings

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