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From: David Miller <davem@davemloft.net>
To: shemminger@vyatta.com
Cc: djohnson@starentnetworks.com, sakkiped@starentnetworks.com,
	netdev@vger.kernel.org
Subject: Re: Deadlock in IPv6 code while garbage collection on the rwlock protecting the routing tree.
Date: Sat, 23 Jan 2010 02:22:10 -0800 (PST)	[thread overview]
Message-ID: <20100123.022210.56302976.davem@davemloft.net> (raw)
In-Reply-To: <20091223101309.08974d02@nehalam>

From: Stephen Hemminger <shemminger@vyatta.com>
Date: Wed, 23 Dec 2009 10:13:09 -0800

> With RCU, you can safely acquire a spinlock inside rcu_read_lock
> section.  The only issue is that the entry being modified might already
> be in process of being deleted (ie. modifying a dead route).
> 
> Probably simpler to just get rid of rwlock entirely, go with a spinlock
> for now.  Reader/writer locks are slower than spin locks and even if
> lock is highly read contended, it is not held for long.
> 
> IPV6 routing table is using much simpler algorithms on the assumption
> that IPV6 was going to solve the CIDR address explosion problem. That
> assumption will probably not hold up, and having a trie (TRASH) version
> of IPV6 routing table with RCU would be a good research project for
> some graduate student.

This is all well and good, but meanwhile someone does need to
fix the deadlock originally reported here :-)

  reply	other threads:[~2010-01-23 10:21 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-12-22 21:57 Deadlock in IPv6 code while garbage collection on the rwlock protecting the routing tree Akkipeddi, Srinivas
2009-12-22 22:36 ` Stephen Hemminger
2009-12-23 17:44   ` Dave Johnson
2009-12-23 18:13     ` Stephen Hemminger
2010-01-23 10:22       ` David Miller [this message]
2010-01-26  9:48         ` Jarek Poplawski
2010-01-26 10:35           ` Jarek Poplawski
2010-01-27  9:59             ` [PATCH] ipv6: Fix possible NULL dereference in icmp6_dst_alloc Jarek Poplawski
2010-01-27 10:14               ` David Miller
2010-01-27 10:34                 ` Jarek Poplawski
2010-01-27 11:04                   ` David Miller
2010-01-27 12:17                     ` Jarek Poplawski
2010-01-27 12:23                       ` David Miller
2010-01-27 12:43                         ` Jarek Poplawski
2010-01-27 13:14                           ` David Miller
2010-01-27 13:28                             ` Jarek Poplawski
2010-01-27 12:35                       ` Atis Elsts

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