netdev - Re: b44: Reset due to FIFO overflow.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1277723370.4235.388.camel@edumazet-laptop>
Date:	Mon, 28 Jun 2010 13:09:30 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	James Courtier-Dutton <james.dutton@...il.com>
Cc:	Mitchell Erblich <erblichs@...thlink.net>, netdev@...r.kernel.org
Subject: Re: b44: Reset due to FIFO overflow.

Le lundi 28 juin 2010 à 11:17 +0100, James Courtier-Dutton a écrit :
> On 28 June 2010 11:00, Eric Dumazet <eric.dumazet@...il.com> wrote:
> >
> > Problem is we receive a spike of RX network frames (possibly UDP or some
> > other RX only trafic), and chip raises an RX fifo overflow _error_
> > indication.
> >
> 
> The cause of the RX overflow is in my case is TCP.
> It is reproducible in mythtv.
> While watching LiveTV, press "s" for the program guide.
> The program guide is implemented into mythtv by a SQL query that
> results in a large response.
> The kernel is probably not servicing the RX FIFO quickly enough due to
> it being busy doing something else. In this case, probably a video
> mode switch.
> 

Thats strange, b44 has a big RX ring... and tcp sender should wait for
ACK...

> > Some hardware are buggy enough that such error indication is fatal and
> > _require_ hardware reset. Thats life. I suspect b44 driver doing a full
> > reset is not a random guess from driver author, but to avoid a complete
> > NIC lockup.
> >
> 
> Interesting, which hardware, apart from the b44, is it that "requires"
> a hardware reset after a RX FIFO overflow.

Just take a look at some net drivers and you'll see some of them have
this requirement.

rtl8169_rx_interrupt()
...
	if (status & RxFOVF) {
		rtl8169_schedule_work(dev, rtl8169_reset_task);
		dev->stats.rx_fifo_errors++;
	}




--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html