From: Anton Blanchard <anton@samba•org>
To: jes@trained-monkey•org
Cc: kuznet@ms2•inr.ac.ru, netdev@oss•sgi.com
Subject: acenic lockup
Date: Wed, 7 May 2003 17:06:57 +1000 [thread overview]
Message-ID: <20030507070657.GC30976@krispykreme> (raw)
Hi,
Ive got a bucketload of acenic adapters in a ppc64 box. I get random
tx timeouts, I suspect there is a missing memory barrier (power4 is
good at catching those). Still looking.
I did manage to lock a card up in ace_start_xmit:
restart:
...
if (tx_ring_full(ap, ap->tx_ret_csm, idx))
goto overflow;
...
overflow:
/*
* This race condition is unavoidable with lock-free drivers.
* We wake up the queue _before_ tx_prd is advanced, so that we
* can
* enter hard_start_xmit too early, while tx ring still looks
* closed.
* This happens ~1-4 times per 100000 packets, so that we can
* allow
* to loop syncing to other CPU. Probably, we need an additional
* wmb() in ace_tx_intr as well.
*
* Note that this race is relieved by reserving one more entry
* in tx ring than it is necessary (see original non-SG driver).
* However, with SG we need to reserve 2*MAX_SKB_FRAGS+1, which
* is already overkill.
*
* Alternative is to return with 1 not throttling queue. In this
* case loop becomes longer, no more useful effects.
*/
barrier();
goto restart;
Its stuck there and never coming out. Alexey: I have a feeling you
wrote this code, is that correct? :)
Anton
next reply other threads:[~2003-05-07 7:06 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-07 7:06 Anton Blanchard [this message]
2003-05-07 6:43 ` acenic lockup David S. Miller
2003-05-07 17:06 ` Alexey Kuznetsov
2003-05-07 19:34 ` David S. Miller
2003-05-07 22:21 ` Alexey Kuznetsov
2003-05-08 16:00 ` David S. Miller
2003-05-08 17:11 ` Jeff Garzik
2003-05-08 16:09 ` David S. Miller
2003-05-08 17:27 ` Jeff Garzik
2003-05-14 11:40 ` Jamal Hadi
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