From: "Américo Wang" <xiyou.wangcong@gmail.com>
To: David Miller <davem@davemloft.net>
Cc: paulmck@linux.vnet.ibm.com, peterz@infradead.org,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: 2.6.34-rc1: rcu lockdep bug?
Date: Fri, 12 Mar 2010 16:59:33 +0800 [thread overview]
Message-ID: <2375c9f91003120059g771d162fxefc21beb2ab17b4d@mail.gmail.com> (raw)
In-Reply-To: <20100312.000705.225033546.davem@davemloft.net>
On Fri, Mar 12, 2010 at 4:07 PM, David Miller <davem@davemloft.net> wrote:
> From: Américo Wang <xiyou.wangcong@gmail.com>
> Date: Fri, 12 Mar 2010 15:56:03 +0800
>
>> Ok, after decoding the lockdep output, it looks like that
>> netif_receive_skb() should call rcu_read_lock_bh() instead of rcu_read_lock()?
>> But I don't know if all callers of netif_receive_skb() are in softirq context.
>
> Normally, netif_receive_skb() is invoked from softirq context.
>
> However, via netpoll it can be invoked essentially from any context.
>
> But, when this happens, the networking receive path makes amends such
> that this works fine. That's what the netpoll_receive_skb() check in
> netif_receive_skb() is for. That check makes it bail out early if the
> call to netif_receive_skb() is via a netpoll invocation.
>
Oh, I see. This means we should call rcu_read_lock_bh() instead.
If Paul has no objections, I will send a patch for this.
Thanks much, David!
next prev parent reply other threads:[~2010-03-12 8:59 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <2375c9f91003110205v1d7f00bfk89472cb11bd985d3@mail.gmail.com>
[not found] ` <20100311134556.GA6344@linux.vnet.ibm.com>
[not found] ` <20100311161751.GA3804@hack>
2010-03-12 7:56 ` 2.6.34-rc1: rcu lockdep bug? Américo Wang
2010-03-12 8:07 ` David Miller
2010-03-12 8:59 ` Américo Wang [this message]
2010-03-12 11:11 ` Eric Dumazet
2010-03-12 13:11 ` Américo Wang
2010-03-12 13:37 ` Eric Dumazet
2010-03-13 5:33 ` Américo Wang
2010-03-13 21:58 ` Paul E. McKenney
2010-03-15 1:08 ` Américo Wang
2010-03-15 3:10 ` Américo Wang
2010-03-15 9:39 ` Américo Wang
2010-03-15 10:04 ` Eric Dumazet
2010-03-15 10:12 ` Américo Wang
2010-03-15 10:41 ` Eric Dumazet
2010-03-16 10:26 ` Américo Wang
2010-03-12 22:03 ` Paul E. McKenney
2010-03-13 5:31 ` Américo Wang
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