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SubjectRe: brlock_is_locked()?
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   From: Brad Chapman <kakadu_croc@yahoo.com>
Date: Wed, 22 Aug 2001 11:53:51 -0700 (PDT)

It's not really a deficiency. Rusty apparently decided that in
order to be SMP-compliant and to prevent Oopses, that the unregistration
function should grab the brlock so that all the packets would pass through
the protocol-handling functions.

So arrange you code such that you aren't holding the netproto
lock when you call the unregistration function.

It is possible to shut down all references to whatever you
are unregistering, safely drop the lock, then call the
netfilter unregister routine.

(I checked the brlock code and didn't find any schedule()s; there's
probably a reason for that).

Ummm, this is SMP 101, you can't sleep with a lock held.
The global kernel lock is special in this regard, but all
other SMP locking primitives may not sleep.

Later,
David S. Miller
davem@redhat.com
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