linux-kernel - Re: [PATCH v2 0/5] Re-order scsi_remove_host and sas_remove

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Message-ID: <f101e42e-0aed-b8ce-2f36-cf16d1964f46@huawei.com>
Date:   Fri, 21 Apr 2017 09:34:18 +0100
From:   John Garry <john.garry@...wei.com>
To:     Johannes Thumshirn <jthumshirn@...e.de>,
        "Martin K . Petersen" <martin.petersen@...cle.com>
CC:     James Bottomley <jejb@...ux.vnet.ibm.com>,
        Christoph Hellwig <hch@....de>, Hannes Reinecke <hare@...e.de>,
        Bart Van Assche <Bart.VanAssche@...disk.com>,
        Linux SCSI Mailinglist <linux-scsi@...r.kernel.org>,
        Linux Kernel Mailinglist <linux-kernel@...r.kernel.org>,
        Jinpu Wang <jinpu.wang@...fitbricks.com>, <tj@...nel.org>,
        <wangyijing@...wei.com>, Heyousong <heyousong@...wei.com>,
        "chenqilin (C)" <chenqilin2@...wei.com>,
        "chenqilin (C)" <chenqilin2@...wei.com>,
        Linuxarm <linuxarm@...wei.com>
Subject: Re: [PATCH v2 0/5] Re-order scsi_remove_host and sas_remove_host in
 SAS HBA LLDDs

Thanks Johannes.

@wangyijing, can you test this patchset please (specifically 3/5)? I 
know that you have the modified version of libsas which you dabbled with 
upstreaming.

On 21/04/2017 09:04, Johannes Thumshirn wrote:
> This series re-orders the calls to scsi_remove_host() and sas_remove_host() in
> all SAS HBA drivers (apart from mpt3sas which is doing it correctly). This is
> for two reasons:
> 	1) After the change to recursive removal of sysfs entries, we're
> 	   trying to remove already removed kobjects when doing a
> 	   sas_remove_host() _after_ a scsi_remove_host()
> 	2) the documentation mandates it even (becuase of 1)
>
> Unfortunately this does not completely solve issues with recursive sysfs
> removals in SAS, as libsas has asynchronous behaviour where strong ordering
> would be needed. But I am working on it and I do know other do as well. So if
> anyone else (James, Christoph, Bart, I'm looking at you) has an idea, I do
> have test setups and I'm willing to take input in form of ideas and patches.
>

wangyijing already sent an RFC for fixing this issue (mentioned above), 
which was a signifiagnt rewrite of some of libsas.
I am hoping that he would retry, and that community would 
support/shepherd this activity, or at least say it will be accepted so 
effort is not wasted.

> I also dropped the SDEV_CANCEL state change for now. We re-evaluate it once we
> have an idea how to tackle the ordering issues and place it into
> sas_unregister_ha() as per James' comment.
>
> Thanks,
> 	Johannes

Thanks

>
> Johannes Thumshirn (5):
>   scsi: isci: remove the SAS host after the SCSI host
>   aic94xx: remove the SAS host after the SCSI host
>   scsi: hisi_sas: remove the SAS host after the SCSI host
>   mvsas: remove the SAS host after the SCSI host
>   scsi: pm8001: remove the SAS host after the SCSI host
>
>  drivers/scsi/aic94xx/aic94xx_init.c   | 7 ++++---
>  drivers/scsi/hisi_sas/hisi_sas_main.c | 4 ++--
>  drivers/scsi/isci/init.c              | 3 ++-
>  drivers/scsi/mvsas/mv_init.c          | 6 ++++--
>  drivers/scsi/pm8001/pm8001_init.c     | 8 ++++++--
>  5 files changed, 18 insertions(+), 10 deletions(-)
>