(kernel is ppc 2.4.21-pre4)
In bond_enslave() [drivers/net/bonding.c]:
write_lock_irqsave(&bond->lock, flags);
...
err = netdev_set_master(slave_dev, master_dev);
...
write_unlock_irqrestore(&bond->lock, flags);
In netdev_set_master() [net/core/dev.c]:
rtmsg_ifinfo(RTM_NEWLINK, slave, IFF_SLAVE);
In rtmsg_ifinfo() [net/core/rtnetlink.c]:
skb = alloc_skb(size, GFP_KERNEL);
...
netlink_broadcast(rtnl, skb, 0, RTMGRP_LINK, GFP_KERNEL);
Doesn't this admit the possibility of sleeping with interrupts disabled?
I found it because I'm working on a driver that uses a master-slave
relationship like the bonding driver, and decided I didn't really need to
disable interrupts, so I tried using write_lock_bh() instead. The result
was an "alloc_skb called nonatomically from interrupt" message because
write_lock_bh() increments the local BH count (which seems reasonable).
A bigger question: Why are the IRQ check and the BH check inconsistent?
That is, local_bh_count() says "yes" if you are currently running in BH
context OR have disabled BHs; however, local_irq_count() says "yes" if you
are currently running in interrupt context, but it says nothing (as far as
I have seen) about whether IRQs are enabled or disabled. Is this (a) the
Right Way, (b) something that's more trouble to fix than to be burned-by
once and then avoid for the rest of your life, or (c) totally horked?
--
Dan Eble <dane@aiinet.com> _____ .
| _ |/|
Applied Innovation Inc. | |_| | |
http://www.aiinet.com/ |__/|_|_|
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