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,
virtualization@lists.linux-foundation.org,
target-devel@vger.kernel.org, stefanha@redhat.com
Subject: Re: [PATCH 09/17] vhost scsi: fix cmd completion race
Date: Fri, 30 Oct 2020 17:04:12 +0100 [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
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prev parent reply other threads:[~2020-10-30 16:04 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1603326903-27052-1-git-send-email-michael.christie@oracle.com>
[not found] ` <1603326903-27052-5-git-send-email-michael.christie@oracle.com>
2020-10-22 5:22 ` [PATCH 04/17] vhost: prep vhost_dev_init users to handle failures kernel test robot
2020-11-02 5:57 ` Jason Wang
2020-11-03 10:04 ` Dan Carpenter
[not found] ` <1603326903-27052-2-git-send-email-michael.christie@oracle.com>
2020-10-26 3:33 ` [PATCH 01/17] vhost scsi: add lun parser helper Jason Wang
[not found] ` <1603326903-27052-4-git-send-email-michael.christie@oracle.com>
2020-10-26 3:34 ` [PATCH 03/17] vhost net: use goto error handling in open Jason Wang
[not found] ` <1603326903-27052-8-git-send-email-michael.christie@oracle.com>
2020-10-26 3:51 ` [PATCH 07/17] vhost scsi: support delayed IO vq creation Jason Wang
[not found] ` <49c2fc29-348c-06db-4823-392f7476d318@oracle.com>
2020-10-28 1:55 ` Jason Wang
2020-10-30 8:47 ` Michael S. Tsirkin
2020-11-02 6:36 ` Jason Wang
2020-11-02 6:49 ` Jason Wang
2020-10-29 21:47 ` [PATCH 00/17 V3] vhost: fix scsi cmd handling and cgroup support Michael S. Tsirkin
[not found] ` <1603326903-27052-10-git-send-email-michael.christie@oracle.com>
2020-10-30 8:51 ` [PATCH 09/17] vhost scsi: fix cmd completion race Michael S. Tsirkin
2020-10-30 16:04 ` Paolo Bonzini [this message]
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