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From: Paolo Bonzini <pbonzini@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>,
	Mike Christie <michael.christie@oracle.com>
Cc: martin.petersen@oracle.com, linux-scsi@vger.kernel.org,
	target-devel@vger.kernel.org, jasowang@redhat.com,
	stefanha@redhat.com, virtualization@lists.linux-foundation.org
Subject: Re: [PATCH 09/17] vhost scsi: fix cmd completion race
Date: Fri, 30 Oct 2020 16:04:12 +0000	[thread overview]
Message-ID: <5c319f1a-cf4c-f522-ecde-5b6b5a2e1ddd@redhat.com> (raw)
In-Reply-To: <20201030045053-mutt-send-email-mst@kernel.org>

On 30/10/20 09:51, Michael S. Tsirkin wrote:
> On Wed, Oct 21, 2020 at 07:34:55PM -0500, Mike Christie wrote:
>> We might not do the final se_cmd put from vhost_scsi_complete_cmd_work.
>> When the last put happens a little later then we could race where
>> vhost_scsi_complete_cmd_work does vhost_signal, the guest runs and sends
>> more IO, and vhost_scsi_handle_vq runs but does not find any free cmds.
>>
>> This patch has us delay completing the cmd until the last lio core ref
>> is dropped. We then know that once we signal to the guest that the cmd
>> is completed that if it queues a new command it will find a free cmd.
>>
>> Signed-off-by: Mike Christie <michael.christie@oracle.com>
> 
> Paolo, could you review this one?

I don't know how LIO does all the callbacks, honestly (I have only ever
worked on the virtio-scsi driver, not vhost-scsi, and I have only ever
reviewed some virtio-scsi spec bits of vhost-scsi).

The vhost_scsi_complete_cmd_work parts look fine, but I have no idea why
vhost_scsi_queue_data_in and vhost_scsi_queue_status call.

Paolo

  reply	other threads:[~2020-10-30 16:04 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-22  0:34 [PATCH 00/17 V3] vhost: fix scsi cmd handling and cgroup support Mike Christie
2020-10-22  0:34 ` [PATCH 01/17] vhost scsi: add lun parser helper Mike Christie
2020-10-26  3:33   ` Jason Wang
2020-10-22  0:34 ` [PATCH 02/17] vhost: remove work arg from vhost_work_flush Mike Christie
2020-10-22  0:51   ` Chaitanya Kulkarni
2020-10-22  0:34 ` [PATCH 03/17] vhost net: use goto error handling in open Mike Christie
2020-10-22  0:45   ` Chaitanya Kulkarni
2020-10-26  3:34   ` Jason Wang
2020-10-22  0:34 ` [PATCH 04/17] vhost: prep vhost_dev_init users to handle failures Mike Christie
2020-10-22  5:22   ` kernel test robot
2020-10-23 16:15   ` Mike Christie
2020-11-02  5:57   ` Jason Wang
2020-11-03 10:04   ` Dan Carpenter
2020-10-22  0:34 ` [PATCH 05/17] vhost: move vq iovec allocation to dev init time Mike Christie
2020-10-22  0:34 ` [PATCH 06/17] vhost: support delayed vq creation Mike Christie
2020-10-22  0:34 ` [PATCH 07/17] vhost scsi: support delayed IO " Mike Christie
2020-10-26  3:51   ` Jason Wang
2020-10-27  5:47     ` Mike Christie
2020-10-28  1:55       ` Jason Wang
2020-10-30  8:47       ` Michael S. Tsirkin
2020-10-30 16:30         ` Mike Christie
2020-10-30 17:26           ` Mike Christie
2020-11-01 22:06         ` Mike Christie
2020-11-02  6:36         ` Jason Wang
2020-11-02  6:49           ` Jason Wang
2020-11-02 16:19             ` Mike Christie
2020-10-22  0:34 ` [PATCH 08/17] vhost scsi: alloc cmds per vq instead of session Mike Christie
2020-10-22  0:34 ` [PATCH 09/17] vhost scsi: fix cmd completion race Mike Christie
2020-10-27 13:07   ` Maurizio Lombardi
2020-10-30  8:51   ` Michael S. Tsirkin
2020-10-30 16:04     ` Paolo Bonzini [this message]
2020-10-22  0:34 ` [PATCH 10/17] vhost scsi: Add support for LUN resets Mike Christie
2020-10-22  0:34 ` [PATCH 11/17] vhost scsi: remove extra flushes Mike Christie
2020-10-22  0:34 ` [PATCH 12/17] vhost poll: fix coding style Mike Christie
2020-10-22  0:39   ` Chaitanya Kulkarni
2020-10-22  0:34 ` [PATCH 13/17] vhost: support multiple worker threads Mike Christie
2020-10-22  0:35 ` [PATCH 14/17] vhost: poll support support multiple workers Mike Christie
2020-10-22  0:35 ` [PATCH 15/17] host: support delayed vq creation Mike Christie
2020-10-22  0:50   ` Mike Christie
2020-10-22  0:35 ` [PATCH 16/17] vhost scsi: multiple worker support Mike Christie
2020-10-22  0:35 ` [PATCH 17/17] vhost scsi: drop submission workqueue Mike Christie
2020-10-29 21:47 ` [PATCH 00/17 V3] vhost: fix scsi cmd handling and cgroup support Michael S. Tsirkin
2020-10-29 22:19   ` Mike Christie

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