From: Elad Nachman <eladv6@gmail.com>
To: Ferruh Yigit <ferruh.yigit@intel.com>
Cc: Eric Christian <erclists@gmail.com>, dev <dev@dpdk.org>,
Igor Ryzhov <iryzhov@nfware.com>
Subject: Re: [dpdk-dev] [PATCH v2] kni: Fix request overwritten
Date: Mon, 4 Oct 2021 17:25:19 +0300 [thread overview]
Message-ID: <CACXF7qna7NexGNtpmjoC6k75V4=iOXQA7nTuwAC0cWwOEZu_DA@mail.gmail.com> (raw)
In-Reply-To: <3ae193df-292c-4907-df4a-88ce3d6735fc@intel.com>
1. Userspace will get an error
2. Waiting with rtnl locked causes a deadlock; waiting with rtnl unlocked
for interface down command causes a crash because of a race condition in
the device delete/unregister list in the kernel.
FYI,
Elad.
בתאריך יום ב׳, 4 באוק׳ 2021, 17:13, מאת Ferruh Yigit <
ferruh.yigit@intel.com>:
> On 10/4/2021 2:09 PM, Elad Nachman wrote:
> > Hi,
> >
> > EAGAIN is propogated back to the kernel and to the caller.
> >
>
> So will the user get an error, or it will be handled by the kernel and
> retried?
>
> > We cannot retry from the kni kernel module since we hold the rtnl lock.
> >
>
> Why not? We are already waiting until a command time out, like
> 'kni_net_open()'
> can retry if 'kni_net_process_request()' returns '-EAGAIN'. And we can
> limit the
> number of retry for safety.
>
> > FYI,
> >
> > Elad
> >
> > בתאריך יום ב׳, 4 באוק׳ 2021, 16:05, מאת Ferruh Yigit <
> > ferruh.yigit@intel.com>:
> >
> >> On 9/24/2021 11:54 AM, Elad Nachman wrote:
> >>> Fix lack of multiple KNI requests handling support by introducing a
> >>> request in progress flag which will fail additional requests with
> >>> EAGAIN return code if the original request has not been processed
> >>> by user-space.
> >>>
> >>> Bugzilla ID: 809
> >>
> >> Hi Eric,
> >>
> >> Can you please test this patch, if it solves the issue you reported?
> >>
> >>>
> >>> Signed-off-by: Elad Nachman <eladv6@gmail.com>
> >>> ---
> >>> kernel/linux/kni/kni_net.c | 9 +++++++++
> >>> lib/kni/rte_kni.c | 2 ++
> >>> lib/kni/rte_kni_common.h | 1 +
> >>> 3 files changed, 12 insertions(+)
> >>>
> >>
> >> <...>
> >>
> >>> @@ -123,7 +124,15 @@ kni_net_process_request(struct net_device *dev,
> >> struct rte_kni_request *req)
> >>>
> >>> mutex_lock(&kni->sync_lock);
> >>>
> >>> + /* Check that existing request has been processed: */
> >>> + cur_req = (struct rte_kni_request *)kni->sync_kva;
> >>> + if (cur_req->req_in_progress) {
> >>> + ret = -EAGAIN;
> >>
> >> Overall logic in the KNI looks good to me, this helps to serialize the
> >> requests
> >> even for async ones.
> >>
> >> But can you please clarify how it behaves in the kernel side with
> '-EAGAIN'
> >> return type? Will linux call the ndo again, or will it just fail.
> >>
> >> If it just fails should we handle the re-try on '-EAGAIN' within the kni
> >> module?
> >>
> >>
>
>
next prev parent reply other threads:[~2021-10-04 14:25 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-24 10:54 Elad Nachman
2021-10-04 13:01 ` Ferruh Yigit
2021-10-04 13:09 ` Elad Nachman
2021-10-04 14:03 ` Ferruh Yigit
2021-10-04 14:25 ` Elad Nachman [this message]
2021-10-04 14:51 ` Ferruh Yigit
2021-10-04 14:58 ` Elad Nachman
2021-10-04 15:48 ` Ferruh Yigit
2021-10-04 16:18 ` Elad Nachman
2021-10-04 16:59 ` Eric Christian
2021-10-04 18:27 ` Elad Nachman
2021-10-08 20:23 ` Ferruh Yigit
2021-10-08 21:11 ` Ferruh Yigit
2021-10-04 14:14 ` Eric Christian
2021-10-04 14:56 ` Ferruh Yigit
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='CACXF7qna7NexGNtpmjoC6k75V4=iOXQA7nTuwAC0cWwOEZu_DA@mail.gmail.com' \
--to=eladv6@gmail.com \
--cc=dev@dpdk.org \
--cc=erclists@gmail.com \
--cc=ferruh.yigit@intel.com \
--cc=iryzhov@nfware.com \
/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).