netdev - Re: [PATCH v3 10/12] l2tp: Add L2TP ethernet pseudowire support

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Message-ID: <4BB31761.2090906@katalix.com>
Date:	Wed, 31 Mar 2010 10:35:29 +0100
From:	James Chapman <jchapman@...alix.com>
To:	Stephen Hemminger <shemminger@...tta.com>
CC:	netdev@...r.kernel.org
Subject: Re: [PATCH v3 10/12] l2tp: Add L2TP ethernet pseudowire support

Stephen Hemminger wrote:
> On Tue, 30 Mar 2010 17:18:19 +0100
> James Chapman <jchapman@...alix.com> wrote:
> 
>> +struct l2tp_eth_net {
>> +	struct list_head l2tp_eth_dev_list;
>> +	rwlock_t l2tp_eth_lock;
>> +};
> 
> Reader/write locks are discouraged because they are slower than
> spin locks.  If you have lots of readers use RCU, if reading
> is infrequent just use a spin lock.

Ok. In doing the conversion of the rwlocks in l2tp_core.c, I'm finding
that some list access primitives don't have rcu equivalents, namely
list_is_last(), list_for_each_entry_safe(). Is this intentional? Should
I add the missing ones in a separate patch?


-- 
James Chapman
Katalix Systems Ltd
http://www.katalix.com
Catalysts for your Embedded Linux software development

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