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From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Jiayu Hu <jiayu.hu@intel.com>, dev@dpdk.org
Cc: chenbo.xia@intel.com, yinan.wang@intel.com,
	sunil.pai.g@intel.com, cheng1.jiang@intel.com
Subject: Re: [dpdk-dev] [PATCH v2 3/4] vhost: avoid deadlock on async register
Date: Tue, 13 Apr 2021 13:33:09 +0200	[thread overview]
Message-ID: <e50e1845-6bc7-014b-14db-a763d88fbaba@redhat.com> (raw)
In-Reply-To: <1617368642-131298-4-git-send-email-jiayu.hu@intel.com>



On 4/2/21 3:04 PM, Jiayu Hu wrote:
> Users can register async copy device in vring_state_changed(),
> when vhost queue is enabled. However, a deadlock occurs inside
> rte_vhost_async_channel_register(), if VHOST_USER_F_PROTOCOL_FEATURES
> is not supported, as vhost_user_msg_handler() takes vq->access_lock
> before calling vhost_user_set_vring_kick().
> 
> This patch avoids async register deadlock by removing calling
> vring_state_changed() in vhost_user_set_vring_kick(). It's safe
> as vhost_user_msg_handler() will call vring_state_changed() anyway.
> 
> Signed-off-by: Jiayu Hu <jiayu.hu@intel.com>
> ---
>  lib/librte_vhost/vhost_user.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index 44c0452..8f0eba6 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -1918,9 +1918,6 @@ vhost_user_set_vring_kick(struct virtio_net **pdev, struct VhostUserMsg *msg,
>  	 */
>  	if (!(dev->features & (1ULL << VHOST_USER_F_PROTOCOL_FEATURES))) {
>  		vq->enabled = true;
> -		if (dev->notify_ops->vring_state_changed)
> -			dev->notify_ops->vring_state_changed(
> -				dev->vid, file.index, 1);
>  	}
>  
>  	if (vq->ready) {
> 

As replied earlier on v1, I agree the call to vring_state_changed here
is not needed. But it might not be enough, there are other cases where
you could have issues.

Please add stable and Fixes tag.

Thanks,
Maxime


  reply	other threads:[~2021-04-13 11:33 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-17 12:56 [dpdk-dev] [PATCH 0/4] Refactor async vhost control path Jiayu Hu
2021-03-17 12:56 ` [dpdk-dev] [PATCH 1/4] vhost: fix uninitialized vhost queue Jiayu Hu
2021-03-26 15:14   ` Maxime Coquelin
2021-03-17 12:56 ` [dpdk-dev] [PATCH 2/4] vhost: remove unnecessary free Jiayu Hu
2021-03-29 15:03   ` Maxime Coquelin
2021-03-17 12:56 ` [dpdk-dev] [PATCH 3/4] vhost: avoid deadlock on async register Jiayu Hu
2021-03-29 15:19   ` Maxime Coquelin
2021-03-30  1:20     ` Hu, Jiayu
2021-04-13  9:37       ` Maxime Coquelin
2021-03-17 12:56 ` [dpdk-dev] [PATCH 4/4] doc: update async vhost register/unregister Jiayu Hu
2021-04-02 13:03 ` [dpdk-dev] [PATCH v2 0/4] Refactor async vhost control path Jiayu Hu
2021-04-02  8:06   ` Wang, Yinan
2021-04-02 13:03   ` [dpdk-dev] [PATCH v2 1/4] vhost: fix uninitialized vhost queue Jiayu Hu
2021-04-13 11:30     ` Maxime Coquelin
2021-04-02 13:04   ` [dpdk-dev] [PATCH v2 2/4] vhost: remove unnecessary free Jiayu Hu
2021-04-02 13:04   ` [dpdk-dev] [PATCH v2 3/4] vhost: avoid deadlock on async register Jiayu Hu
2021-04-13 11:33     ` Maxime Coquelin [this message]
2021-04-14  1:40       ` Hu, Jiayu
2021-04-14 10:08         ` Maxime Coquelin
2021-04-15  1:08           ` Hu, Jiayu
2021-04-15  7:09             ` Maxime Coquelin
2021-04-16  2:19               ` Hu, Jiayu
2021-04-16  6:35                 ` Maxime Coquelin
2021-04-16  8:18                   ` Hu, Jiayu
2021-04-16  8:33                     ` Maxime Coquelin
2021-04-19  4:10                       ` Hu, Jiayu
2021-04-19  7:13                         ` Maxime Coquelin
2021-04-19  9:02                           ` Hu, Jiayu
2021-04-02 13:04   ` [dpdk-dev] [PATCH v2 4/4] doc: update async vhost register/unregister Jiayu Hu
2021-04-20  8:57   ` [dpdk-dev] [PATCH v3 0/4] Refactor async vhost control path Jiayu Hu
2021-04-20  8:57     ` [dpdk-dev] [PATCH v3 1/4] vhost: fix uninitialized vhost queue Jiayu Hu
2021-04-20  8:57     ` [dpdk-dev] [PATCH v3 2/4] vhost: remove unnecessary free Jiayu Hu
2021-04-20  8:57     ` [dpdk-dev] [PATCH v3 3/4] vhost: fix unnecessary vring_state_changed call Jiayu Hu
2021-04-20  9:39       ` Maxime Coquelin
2021-04-21  1:36         ` Xia, Chenbo
2021-04-20  8:57     ` [dpdk-dev] [PATCH v3 4/4] doc: update async vhost register/unregister Jiayu Hu
2021-04-20  9:31       ` Maxime Coquelin
2021-04-28  2:05     ` [dpdk-dev] [PATCH v3 0/4] Refactor async vhost control path Xia, Chenbo

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