Messages in this thread | | | Date | Mon, 15 Mar 2010 11:10:06 +0800 | Subject | Re: 2.6.34-rc1: rcu lockdep bug? | From | Américo Wang <> |
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2010/3/15 Américo Wang <xiyou.wangcong@gmail.com>: > On Sat, Mar 13, 2010 at 01:58:38PM -0800, Paul E. McKenney wrote: >>On Sat, Mar 13, 2010 at 01:33:56PM +0800, Américo Wang wrote: >>> On Fri, Mar 12, 2010 at 02:37:38PM +0100, Eric Dumazet wrote: >>> >Le vendredi 12 mars 2010 à 21:11 +0800, Américo Wang a écrit : >>> > >>> >> Oh, but lockdep complains about rcu_read_lock(), it said >>> >> rcu_read_lock() can't be used in softirq context. >>> >> >>> >> Am I missing something? >>> > >>> >Well, lockdep might be dumb, I dont know... >>> > >>> >I suggest you read rcu_read_lock_bh kernel doc : >>> > >>> >/** >>> > * rcu_read_lock_bh - mark the beginning of a softirq-only RCU critical >>> >section >>> > * >>> > * This is equivalent of rcu_read_lock(), but to be used when updates >>> > * are being done using call_rcu_bh(). Since call_rcu_bh() callbacks >>> > * consider completion of a softirq handler to be a quiescent state, >>> > * a process in RCU read-side critical section must be protected by >>> > * disabling softirqs. Read-side critical sections in interrupt context >>> > * can use just rcu_read_lock(). >>> > * >>> > */ >>> > >>> > >>> >Last sentence being perfect : >>> > >>> >Read-side critical sections in interrupt context >>> >can use just rcu_read_lock(). >>> > >>> >>> Yeah, right, then it is more likely to be a bug of rcu lockdep. >>> Paul is looking at it. >> >>Except that it seems to be working correctly for me... >> > > Hmm, then I am confused. The only possibility here is that this is > a lockdep bug... >
I believe so...
Peter, this looks odd:
kernel: (usbfs_mutex){+.?...}, at: [<ffffffff8146419f>] netif_receive_skb+0xe7/0x819
netif_receive_skb() never has a chance to take usbfs_mutex. How can this comes out? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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