From: "Fu, Patrick" <patrick.fu@intel.com>
To: Maxime Coquelin <maxime.coquelin@redhat.com>,
"dev@dpdk.org" <dev@dpdk.org>,
"Xia, Chenbo" <chenbo.xia@intel.com>
Cc: "Wang, Zhihong" <zhihong.wang@intel.com>,
"Jiang, Cheng1" <cheng1.jiang@intel.com>
Subject: Re: [dpdk-dev] [PATCH v3 4/4] vhost: fix async register/unregister deadlock
Date: Fri, 9 Oct 2020 10:54:37 +0000 [thread overview]
Message-ID: <MWHPR11MB0032C146E98DABE535A0577884080@MWHPR11MB0032.namprd11.prod.outlook.com> (raw)
In-Reply-To: <82d290c9-02f0-a521-f38f-c5a726db99aa@redhat.com>
> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Monday, October 5, 2020 10:26 PM
> To: Fu, Patrick <patrick.fu@intel.com>; dev@dpdk.org; Xia, Chenbo
> <chenbo.xia@intel.com>
> Cc: Wang, Zhihong <zhihong.wang@intel.com>; Jiang, Cheng1
> <cheng1.jiang@intel.com>
> Subject: Re: [PATCH v3 4/4] vhost: fix async register/unregister deadlock
>
>
>
> On 9/29/20 11:29 AM, Patrick Fu wrote:
> > When async register/unregister function is invoked in certain vhost
> > event callbacks (e.g. vring state change), deadlock may occur due to
> > recursive spinlock acquire. This patch removes unnecessary spinlock
> > from register API and use trylock() primitive in the unregister API
> > to avoid deadlock.
>
> I am not convinced it is unnecessary in every cases.
>
>
> > Fixes: 78639d54563a ("vhost: introduce async enqueue registration API")
> >
> > Signed-off-by: Patrick Fu <patrick.fu@intel.com>
> > ---
> > lib/librte_vhost/vhost.c | 13 +++++++------
> > lib/librte_vhost/vhost_user.c | 4 ++--
> > 2 files changed, 9 insertions(+), 8 deletions(-)
> >
> > diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
> > index 05b578c2f..ba504a00a 100644
> > --- a/lib/librte_vhost/vhost.c
> > +++ b/lib/librte_vhost/vhost.c
> > @@ -1577,8 +1577,6 @@ int rte_vhost_async_channel_register(int vid,
> uint16_t queue_id,
> > ops->transfer_data == NULL))
> > return -1;
> >
> > - rte_spinlock_lock(&vq->access_lock);
> > -
>
> What if a virtqueue is being destroyed while this function is called?
>
Yes, this is a scenario that access_lock may help. I will add spinlock back in v4.
Thanks,
Patrick
next prev parent reply other threads:[~2020-10-09 10:54 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-11 1:53 [dpdk-dev] [PATCH v1 0/4] optimize async data path Patrick Fu
2020-09-11 1:53 ` [dpdk-dev] [PATCH v1 1/4] vhost: simplify async copy completion Patrick Fu
2020-09-23 9:07 ` Maxime Coquelin
2020-09-11 1:53 ` [dpdk-dev] [PATCH v1 2/4] vhost: dynamically alloc async memory Patrick Fu
2020-09-23 9:15 ` Maxime Coquelin
2020-09-29 5:55 ` Fu, Patrick
2020-09-11 1:53 ` [dpdk-dev] [PATCH v1 3/4] vhost: fix async vec buf overrun Patrick Fu
2020-09-23 9:21 ` Maxime Coquelin
2020-09-29 2:23 ` Fu, Patrick
2020-09-11 1:53 ` [dpdk-dev] [PATCH v1 4/4] vhost: fix async register/unregister deadlock Patrick Fu
2020-09-29 6:29 ` [dpdk-dev] [PATCH v2 0/4] optimize async data path Patrick Fu
2020-09-29 6:29 ` [dpdk-dev] [PATCH v2 1/4] vhost: simplify async copy completion Patrick Fu
2020-09-29 6:29 ` [dpdk-dev] [PATCH v2 2/4] vhost: dynamically allocate async memory Patrick Fu
2020-09-29 6:29 ` [dpdk-dev] [PATCH v2 3/4] vhost: fix async vector buffer overrun Patrick Fu
2020-09-29 6:29 ` [dpdk-dev] [PATCH v2 4/4] vhost: fix async register/unregister deadlock Patrick Fu
2020-09-29 9:29 ` [dpdk-dev] [PATCH v3 0/4] optimize async data path Patrick Fu
2020-09-29 9:29 ` [dpdk-dev] [PATCH v3 1/4] vhost: simplify async copy completion Patrick Fu
2020-10-05 13:46 ` Maxime Coquelin
2020-10-09 11:16 ` Fu, Patrick
2020-09-29 9:29 ` [dpdk-dev] [PATCH v3 2/4] vhost: dynamically allocate async memory Patrick Fu
2020-10-05 13:50 ` Maxime Coquelin
2020-09-29 9:29 ` [dpdk-dev] [PATCH v3 3/4] vhost: fix async vector buffer overrun Patrick Fu
2020-10-05 14:19 ` Maxime Coquelin
2020-09-29 9:29 ` [dpdk-dev] [PATCH v3 4/4] vhost: fix async register/unregister deadlock Patrick Fu
2020-10-05 14:25 ` Maxime Coquelin
2020-10-09 10:54 ` Fu, Patrick [this message]
2020-10-13 1:45 ` [dpdk-dev] [PATCH v4 0/4] optimize async data path Patrick Fu
2020-10-13 1:45 ` [dpdk-dev] [PATCH v4 1/4] vhost: simplify async copy completion Patrick Fu
2020-10-14 9:28 ` Maxime Coquelin
2020-10-13 1:45 ` [dpdk-dev] [PATCH v4 2/4] vhost: dynamically allocate async memory Patrick Fu
2020-10-14 9:30 ` Maxime Coquelin
2020-10-13 1:45 ` [dpdk-dev] [PATCH v4 3/4] vhost: fix async vector buffer overrun Patrick Fu
2020-10-14 9:33 ` Maxime Coquelin
2020-10-13 1:45 ` [dpdk-dev] [PATCH v4 4/4] vhost: fix async unregister deadlock Patrick Fu
2020-10-14 9:34 ` Maxime Coquelin
2020-10-15 15:40 ` [dpdk-dev] [PATCH v4 0/4] optimize async data path Maxime Coquelin
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