Subject: Re: [PATCH v3 0/7] Enhance libsas hotplug feature
To: <jejb@linux.vnet.ibm.com>, <martin.petersen@oracle.com>
References: <1499670369-44143-1-git-send-email-wangyijing@huawei.com>
CC: <chenqilin2@huawei.com>, <hare@suse.com>, <linux-scsi@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <chenxiang66@hisilicon.com>,
        <huangdaode@hisilicon.com>, <wangkefeng.wang@huawei.com>,
        <zhaohongjiang@huawei.com>, <dingtianhong@huawei.com>,
        <guohanjun@huawei.com>, <yanaijie@huawei.com>, <hch@lst.de>,
        <dan.j.williams@intel.com>, <emilne@redhat.com>, <thenzl@redhat.com>,
        <wefu@redhat.com>, <charles.chenxin@huawei.com>,
        <chenweilong@huawei.com>, <john.garry@huawei.com>
From: wangyijing <wangyijing@huawei.com>
Message-ID: <59687E80.1080807@huawei.com>
Date: Fri, 14 Jul 2017 16:19:12 +0800
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Hi, I'm sorry to say that I have to stop the libsas hotplug improvement work, I will resign from
Huawei, so I have no time and hardware to continue to work at this issue. John is very familiar with
this work, and provide a lot of good suggestions. So if John like, I am glad he could join to work
at this issues, And my colleague Jason Yan could also provide helps.


Thanks!
Yijing.


在 2017/7/10 15:06, Yijing Wang 写道:
> This patchset is based Johannes's patch
> "scsi: sas: scsi_queue_work can fail, so make callers aware"
> 
> Now the libsas hotplug has some issues, Dan Williams report
> a similar bug here before
> https://www.mail-archive.com/linux-scsi@vger.kernel.org/msg39187.html
> 
> The issues we have found
> 1. if LLDD burst reports lots of phy-up/phy-down sas events, some events
>    may lost because a same sas events is pending now, finally libsas topo
>    may different the hardware.
> 2. receive a phy down sas event, libsas call sas_deform_port to remove
>    devices, it would first delete the sas port, then put a destruction
>    discovery event in a new work, and queue it at the tail of workqueue,
>    once the sas port be deleted, its children device will be deleted too,
>    when the destruction work start, it will found the target device has
>    been removed, and report a sysfs warnning.
> 3. since a hotplug process will be devided into several works, if a phy up
>    sas event insert into phydown works, like
>    destruction work  ---> PORTE_BYTES_DMAED (sas_form_port) ---->PHYE_LOSS_OF_SIGNAL
>    the hot remove flow would broken by PORTE_BYTES_DMAED event, it's not
>    we expected, and issues would occur.
> 
> The first patch fix the sas events lost, and the second one introudce wait-complete
> to fix the hotplug order issues.
> 
> v2->v3: some code improvements suggested by Johannes and John,
> 	    split v2 patch 2 into several small pathes.
> v1->v2: some code improvements suggested by John Garry
> 
> Yijing Wang (7):
>   libsas: Use static sas event pool to appease sas event lost
>   libsas: remove unused port_gone_completion
>   libsas: Use new workqueue to run sas event
>   libsas: add sas event wait-complete support
>   libsas: add a new workqueue to run probe/destruct discovery event
>   libsas: add wait-complete support to sync discovery event
>   libsas: release disco mutex during waiting in sas_ex_discover_end_dev
> 
>  drivers/scsi/libsas/sas_discover.c |  58 +++++++---
>  drivers/scsi/libsas/sas_event.c    | 212 ++++++++++++++++++++++++++++++++-----
>  drivers/scsi/libsas/sas_expander.c |  22 +++-
>  drivers/scsi/libsas/sas_init.c     |  21 ++--
>  drivers/scsi/libsas/sas_internal.h |  64 +++++++++++
>  drivers/scsi/libsas/sas_phy.c      |  48 +++------
>  drivers/scsi/libsas/sas_port.c     |  22 ++--
>  include/scsi/libsas.h              |  27 +++--
>  8 files changed, 373 insertions(+), 101 deletions(-)
>