From: Eric Dumazet <eric.dumazet@gmail.com>
To: "Per Dalén" <per.dalen@appeartv.com>
Cc: Claudiu Manoil <claudiu.manoil@freescale.com>, netdev@vger.kernel.org
Subject: Re: BQL support in gianfar causes network hiccup
Date: Tue, 03 Sep 2013 08:42:20 -0700 [thread overview]
Message-ID: <1378222940.7360.34.camel@edumazet-glaptop> (raw)
In-Reply-To: <522595DD.1030600@appeartv.com>
On Tue, 2013-09-03 at 09:55 +0200, Per Dalén wrote:
> Yes, it's weird. The only reason I removed the BQL commit
> (d8a0f1b0af67679bba886784de10d8c21acc4e0e) was because the error Tino
> Keitel had was the similar as mine.
I suspect a genuine race in this driver. BQL only makes this race happen
more often.
gfar_poll_sq() has the following :
/* run Tx cleanup to completion */
if (tx_queue->tx_skbuff[tx_queue->skb_dirtytx])
gfar_clean_tx_ring(tx_queue);
While gfar_poll() has a different method :
if (tx_queue->tx_skbuff[tx_queue->skb_dirtytx]) {
gfar_clean_tx_ring(tx_queue);
has_tx_work = 1;
}
Note the has_tx_work use in gfar_poll() only.
Note that memory barriers seems to be missing.
1) In your cases, is it gfar_poll_sq() or gfar_poll() that is used ?
2) Is the bug happening if only one CPU is used ?
next prev parent reply other threads:[~2013-09-03 15:43 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-02 13:21 BQL support in gianfar causes network hiccup Per Dalén
2013-09-02 13:53 ` Claudiu Manoil
2013-09-02 14:37 ` Per Dalén
2013-09-02 15:35 ` Claudiu Manoil
2013-09-02 16:50 ` Per Dalén
2013-09-03 7:06 ` Claudiu Manoil
2013-09-03 7:55 ` Per Dalén
2013-09-03 15:42 ` Eric Dumazet [this message]
2013-09-03 16:09 ` Claudiu Manoil
2013-09-03 19:33 ` Per Dalén
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