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From: David Miller <davem@davemloft.net>
Subject: Re: Deadlock in Bluetooth code in 2.6.36
Date: Fri, 24 Sep 2010 21:18:24 -0700 (PDT)
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From: "Gustavo F. Padovan" <padovan@profusion.mobi>
Date: Tue, 21 Sep 2010 18:20:12 -0300

> My questions here is on how to fix this properly. Maybe
> sock_alloc_send_skb() should not be used with SOCK_STREAM and reliable
> protocols and I'm not aware of that? And should I use something like
> sk_stream_alloc_skb() instead?
> 
> Any comments are welcome. With lucky we can fix that for 2.6.36 and
> together with others fixes we have queued deliver a fully functional
> L2CAP layer on 2.6.36.

Use sock_alloc_send_skb() as you do now, but if it fails wait for socket
space to become available just like TCP does, then loop back and try to
allocate again if the space-wait doesn't return an error.

I think you should be able to reuse sk_stream_wait_memory() for this
purpose just fine and without any problems.