Cong Wang <xiyou.wangc...@gmail.com> :
[...]
> alloc_skb(GFP_KERNEL) itself is sleeping, so the new wait api is still
> needed.
The task state change warning is the symptom.
The deeply nested alloc_skb is the problem.
Diagnosis: nesting is wrong. It makes zero sense. Fix it and the
implicit task state change problem automagically goes away.
alloc_skb() does not need to be in the "while" loop.
alloc_skb() does not need to be in the {prepare_to_wait/add_wait_queue ...
finish_wait/remove_wait_queue} block.
alloc_tx() is not correctly named: given its original content, it deserves
to be called something like:
"wait_for_decent_tx_drain_and_alloc_by_hand_coz_i_dont_trust_the_mm_subsystem_and_i_dont_know_what_i_want"
I claim that:
- alloc_tx() should only perform the "wait_for_decent_tx_drain" part
- alloc_skb() ought to be done directly in vcc_sendmsg
- alloc_skb() failure can be handled gracefully in vcc_sendmsg
- alloc_skb() may use a (m->msg_flags & MSG_DONTWAIT) dependant
GFP_{KERNEL / ATOMIC} flag
- most of it can be done in a longterm maintenance pain minimizing
way. Call it a side-effect: I don't claim that it *must* be done
this way.
--
Ueimor
