From: "David S. Miller" <davem@davemloft.net>
To: yoshfuji@linux-ipv6.org
Cc: netdev@vger.kernel.org
Subject: Re: [RFC PATCH] [IPV6]: Fix race in route selection.
Date: Fri, 28 Apr 2006 15:58:27 -0700 (PDT) [thread overview]
Message-ID: <20060428.155827.04891779.davem@davemloft.net> (raw)
In-Reply-To: <20060428.020456.35552581.yoshfuji@linux-ipv6.org>
From: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Date: Fri, 28 Apr 2006 02:04:56 +0900 (JST)
> We eliminated rt6_dflt_lock (to protect default router pointer)
> at 2.6.17-rc1, and introduced rt6_select() for general router selection.
> The function is called in the context of rt6_lock read-lock held,
> but this means, we have some race conditions when we do round-robin.
>
> Am I correct?
>
> If so, we should put some spin_lock for serialization.
>
> Comments?
>
> Signed-off-by; YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
>
> Or, should we run whole part of rt6_select() under some lock?
I think the local lock will work and it is fine for now.
I will apply this as-is to fix the bug.
But in the longer term this seems a little bit heavy operation.
Perhaps there is some way to use "xchg()" here? It is just moving a
pointer around for a round robin list, if it could be reduced to just
a single pointer store, we could even do it without atomic operations.
prev parent reply other threads:[~2006-04-28 22:58 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-04-27 17:04 [RFC PATCH] [IPV6]: Fix race in route selection YOSHIFUJI Hideaki / 吉藤英明
2006-04-28 22:58 ` David S. Miller [this message]
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