From: Manfred Spraul <manfred@colorfullife.com>
To: Andrew Morton <akpm@osdl.org>
Cc: linux-kernel@vger.kernel.org, Adam Nielsen <a.nielsen@optushome.com.au>
Subject: Re: [PATCH] Fix kernel lockup in RTL-8169 gigabit ethernet driver
Date: Sat, 03 Apr 2004 13:30:28 +0200 [thread overview]
Message-ID: <406EA054.2020401@colorfullife.com> (raw)
Andrew wrote:
>The logic is faulty, or at least very odd.
>
> tx_left = tp->cur_tx - dirty_tx;
>
> while (tx_left > 0) {
> int entry = dirty_tx % NUM_TX_DESC;
>
> if (!(le32_to_cpu(tp->TxDescArray[entry].status) & OWNbit)) {
> ...
> }
> }
>
>Why is that `if' test there at all? If it ever returns false, the box
>locks up. A BUG_ON(le32_to_cpu(tp->TxDescArray[entry].status) & OWNbit)
>might make more sense.
>
>
tx_left counts packets submitted by hard_xmit_start to the hardware.
Initially OWNbit is set, the packet is owned by the nic. The OWNbit is
cleared by the hardware after the packet was sent. A packet with OWNbit
set means that the nic didn't send it yet to the wire. I think the "else
break;" patch is correct, but someone with docs should confirm that.
Adam: did you see deadlocks that disappeared after applying your patch?
It shouldn't deadlock - it should loop until the nic sends the packet to
the wire. It might take a few msecs, but then it should continue.
Perhaps gcc optimized away the reload from memory and loops on a
register. Or there is another bug that is hidden by your patch.
--
Manfred
next reply other threads:[~2004-04-03 11:30 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-04-03 11:30 Manfred Spraul [this message]
2004-04-03 12:45 ` [PATCH] Fix kernel lockup in RTL-8169 gigabit ethernet driver Francois Romieu
2004-04-04 0:55 ` Malvineous
2004-04-04 9:15 ` Francois Romieu
2004-04-05 21:51 ` Adam Nielsen
2004-04-06 17:11 ` Manfred Spraul
2004-04-06 20:50 ` Francois Romieu
-- strict thread matches above, loose matches on Subject: below --
2004-04-05 23:08 Dieter Nützel
2004-04-06 7:47 ` Francois Romieu
2004-04-03 5:02 Adam Nielsen
2004-04-03 9:27 ` Francois Romieu
2004-04-03 10:07 ` Andrew Morton
2004-04-03 12:13 ` Francois Romieu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=406EA054.2020401@colorfullife.com \
--to=manfred@colorfullife.com \
--cc=a.nielsen@optushome.com.au \
--cc=akpm@osdl.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).