Messages in this thread | | | Subject | Re: 2.6.34-rc1: rcu lockdep bug? | From | Eric Dumazet <> | Date | Mon, 15 Mar 2010 11:41:03 +0100 |
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Le lundi 15 mars 2010 à 18:12 +0800, Américo Wang a écrit : > On Mon, Mar 15, 2010 at 6:04 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote: > > Le lundi 15 mars 2010 à 17:39 +0800, Américo Wang a écrit : > > > >> > >> Ok, I think I found what lockdep really complains about, it is that we took > >> spin_lock in netpoll_poll_lock() which is in hardirq-enabled environment, > >> later, we took another spin_lock with spin_lock_irqsave() in netpoll_rx(), > >> so lockdep thought we broke the locking rule. > >> > >> I don't know why netpoll_rx() needs irq disabled, it looks like that no one > >> takes rx_lock in hardirq context. So can we use spin_lock(&rx_lock) > >> instead? Or am I missing something here? Eric? David? > > > > I am a bit lost. > > > > Could you give the complete picture, because I cannot find it in my > > netdev archives. > > > > Sure, sorry for this. > > Here is the whole thread: > > http://lkml.org/lkml/2010/3/11/100
OK thanks
netpoll_rx() can be called from hard irqs (netif_rx()), so rx_lock definitly needs irq care.
netpoll_poll_lock() does take a spinlock with irq enabled, but its not rx_lock, its napi->poll_lock.
I dont see what could be the problem, is it reproductible with vanilla kernel ?
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