From: "Charles (Chas) Williams" <3chas3@gmail.com>
To: netdev@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Subject: xen-netfront: bug with napi_synchronize()
Date: Thu, 20 Aug 2015 16:50:01 -0400 [thread overview]
Message-ID: <1440103801.2546.14.camel@gmail.com> (raw)
I have seen some hangs in recent versions of the xen-netfront driver.
If I unload or unbind the driver immediately befor bringing up the
interface, I get a hang as show in the traceback here.
...
[ 194.037351] [<ffffffff810ae1a7>] ? msleep+0x27/0x30
[ 194.037358] [<ffffffffa004b48a>] ? xennet_disconnect_backend+0xfa/0x390 [xen_netfront]
[ 194.037364] [<ffffffffa004b789>] ? xennet_remove+0x19/0x60 [xen_netfront]
[ 194.037368] [<ffffffff8132971b>] ? xenbus_dev_remove+0x4b/0xa0
[ 194.037375] [<ffffffff8137bf41>] ? __device_release_driver+0x81/0x120
[ 194.037378] [<ffffffff8137bffd>] ? device_release_driver+0x1d/0x30
[ 194.037382] [<ffffffff8137b340>] ? unbind_store+0xf0/0x150
...
This offset in xennet_disconnect_backend is approximately in the area
of napi_synchronize(). napi_synchronize() does contain an msleep()
and nothing else would really sleep in this routine.
queue->tx_evtchn = queue->rx_evtchn = 0;
queue->tx_irq = queue->rx_irq = 0;
napi_synchronize(&queue->napi);
xennet_release_tx_bufs(queue);
xennet_release_rx_bufs(queue);
Since I never started the interface, I know napi_enable() was never
called on queue->napi. However, what is the expected behavior for
napi_synchronize() on something that was never enabled/disabled?
reply other threads:[~2015-08-20 20:50 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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=1440103801.2546.14.camel@gmail.com \
--to=3chas3@gmail.com \
--cc=netdev@vger.kernel.org \
--cc=xen-devel@lists.xenproject.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).