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Message-ID: <7ad77303-9960-5b8c-f26e-fc825ac57621@huawei.com>
Date: Thu, 31 Jan 2019 10:29:17 +0000
From: John Garry <john.garry@...wei.com>
To: Jason Yan <yanaijie@...wei.com>, <martin.petersen@...cle.com>,
<jejb@...ux.vnet.ibm.com>
CC: <linux-scsi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<zhaohongjiang@...wei.com>, <hare@...e.com>,
<dan.j.williams@...el.com>, <jthumshirn@...e.de>, <hch@....de>,
<huangdaode@...ilicon.com>, <chenxiang66@...ilicon.com>,
<xiexiuqi@...wei.com>, <tj@...nel.org>, <miaoxie@...wei.com>,
Ewan Milne <emilne@...hat.com>, Tomas Henzl <thenzl@...hat.com>
Subject: Re: [PATCH v2 4/7] scsi: libsas: split the replacement of sas disks
in two steps
On 31/01/2019 02:04, Jason Yan wrote:
>
>
> On 2019/1/31 1:22, John Garry wrote:
>> On 30/01/2019 08:24, Jason Yan wrote:
>>> Now if a new device replaced a old device, the sas address will change.
>>
>> Hmmm... not if it's a SATA disk, which would have some same invented SAS
>> address.
>>
>
> Yes, it's only for a SAS disk.
>
>>> We unregister the old device and discover the new device in one
>>> revalidation process. But after we deferred the sas_port_delete(), the
>>> sas port is not deleted when we registering the new port and device.
>>> The sas port cannot be added because the name of the new port is the
>>> same as the old.
>>>
>>> Fix this by doing the replacement in two steps. The first revalidation
>>> only delete the old device and trigger a new revalidation. The second
>>> revalidation discover the new device. To keep the event processing
>>> synchronised to the original event,
>>
>> Did I originally suggest this? It seems to needlessly make the code more
>> complicated.
>>
>
> Yes, my first version was raise a new bcast event, and you said it's not
> synchronised to the original event. Shall I get back to that approach?
Not sure. This patch seems to fix something closely related to that in
"scsi: libsas: fix issue of swapping two sas disks", which I will check
further.
EOM
>
>> we wrapped a loop and added a new
>>> parameter to see if we should revalidate again.
>>>
>>> Signed-off-by: Jason Yan <yanaijie@...wei.com>
>>> CC: chenxiang <chenxiang66@...ilicon.com>
>>> CC: John Garry <john.garry@...wei.com>
>>> CC: Johannes Thumshirn <jthumshirn@...e.de>
>>> CC: Ewan Milne <emilne@...hat.com>
>>> CC: Christoph Hellwig <hch@....de>
>>> CC: Tomas Henzl <thenzl@...hat.com>
>>> CC: Dan Williams <dan.j.williams@...el.com>
>>> CC: Hannes Reinecke <hare@...e.com>
>>> ---
>>> drivers/scsi/libsas/sas_discover.c | 20 +++++++++++++++-----
>>> drivers/scsi/libsas/sas_expander.c | 20 ++++++++++++++------
>>> include/scsi/libsas.h | 2 +-
>>> 3 files changed, 30 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/drivers/scsi/libsas/sas_discover.c
>>> b/drivers/scsi/libsas/sas_discover.c
>>> index ffc571a12916..c825c89fbddd 100644
>>> --- a/drivers/scsi/libsas/sas_discover.c
>>> +++ b/drivers/scsi/libsas/sas_discover.c
>>> @@ -498,12 +498,10 @@ static void sas_discover_domain(struct
>>> work_struct *work)
>>> task_pid_nr(current), error);
>>> }
>>>
>>> -static void sas_revalidate_domain(struct work_struct *work)
>>> +static void sas_do_revalidate_domain(struct asd_sas_port *port, bool
>>> *retry)
>>> {
>>> - struct sas_discovery_event *ev = to_sas_discovery_event(work);
>>> - struct asd_sas_port *port = ev->port;
>>> - struct sas_ha_struct *ha = port->ha;
>>> struct domain_device *ddev = port->port_dev;
>>> + struct sas_ha_struct *ha = port->ha;
>>>
>>> /* prevent revalidation from finding sata links in recovery */
>>> mutex_lock(&ha->disco_mutex);
>>> @@ -520,7 +518,7 @@ static void sas_revalidate_domain(struct
>>> work_struct *work)
>>>
>>> if (ddev && (ddev->dev_type == SAS_FANOUT_EXPANDER_DEVICE ||
>>> ddev->dev_type == SAS_EDGE_EXPANDER_DEVICE))
>>> - sas_ex_revalidate_domain(ddev);
>>> + sas_ex_revalidate_domain(ddev, retry);
>>>
>>> pr_debug("done REVALIDATING DOMAIN on port %d, pid:%d\n",
>>> port->id, task_pid_nr(current));
>>> @@ -532,6 +530,18 @@ static void sas_revalidate_domain(struct
>>> work_struct *work)
>>> sas_probe_devices(port);
>>> }
>>>
>>> +static void sas_revalidate_domain(struct work_struct *work)
>>> +{
>>> + struct sas_discovery_event *ev = to_sas_discovery_event(work);
>>> + struct asd_sas_port *port = ev->port;
>>> + bool retry;
>>> +
>>> + do {
>>> + retry = false;
>>> + sas_do_revalidate_domain(port, &retry);
>>> + } while (retry);
>>> +}
>>> +
>>> /* ---------- Events ---------- */
>>>
>>> static void sas_chain_work(struct sas_ha_struct *ha, struct sas_work
>>> *sw)
>>> diff --git a/drivers/scsi/libsas/sas_expander.c
>>> b/drivers/scsi/libsas/sas_expander.c
>>> index 5cd720f93f96..cdbf8d8a28bf 100644
>>> --- a/drivers/scsi/libsas/sas_expander.c
>>> +++ b/drivers/scsi/libsas/sas_expander.c
>>> @@ -1994,7 +1994,8 @@ static bool dev_type_flutter(enum
>>> sas_device_type new, enum sas_device_type old)
>>> return false;
>>> }
>>>
>>> -static int sas_rediscover_dev(struct domain_device *dev, int phy_id,
>>> bool last)
>>> +static int sas_unregister(struct domain_device *dev, int phy_id, bool
>>> last,
>>> + bool *retry)
>>> {
>>> struct expander_device *ex = &dev->ex_dev;
>>> struct ex_phy *phy = &ex->ex_phy[phy_id];
>>> @@ -2045,7 +2046,12 @@ static int sas_rediscover_dev(struct
>>> domain_device *dev, int phy_id, bool last)
>>> SAS_ADDR(phy->attached_sas_addr));
>>> sas_unregister_devs_sas_addr(dev, phy_id, last);
>>>
>>> - return sas_discover_new(dev, phy_id);
>>> + /* force the next revalidation find this phy and bring it up */
>>> + phy->phy_change_count = -1;
>>> + ex->ex_change_count = -1;
>>> + *retry = true;
>>
>> Ohh, sorry to say, but that's a real hack :)
>>
>
> This is the way sas_resume_port() already in use.
>
>> Could we just add a flag for the expander PHY to force a discovery
>> instead of this?
>>
>
> of course we can add a flag instead of this, but I don't think it worth
> to do this. We have to change the logic of sas_find_bcast_dev() and
> sas_find_bcast_phy() to achieve this. Or we have to add a new function
> to find out which PHY's flag is set.
>
>> I assume that you need to do this as the expander PHY change count will
>> not be modified for the next revalidation (so no discovery on that PHY).
>>
>
> To save one instruction(assign), we have to add two(check and assign)?
> And how to predict if the PHY change count will be modified or not?
> It's unnessesary to do this.
>
>>> +
>>> + return 0;
>>> }
>>>
>>> /**
>>> @@ -2062,7 +2068,8 @@ static int sas_rediscover_dev(struct
>>> domain_device *dev, int phy_id, bool last)
>>> * first phy,for other phys in this port, we add it to the port to
>>> * forming the wide-port.
>>> */
>>> -static void sas_rediscover(struct domain_device *dev, const int phy_id)
>>> +static void sas_rediscover(struct domain_device *dev, const int phy_id,
>>> + bool *retry)
>>> {
>>> struct expander_device *ex = &dev->ex_dev;
>>> struct ex_phy *changed_phy = &ex->ex_phy[phy_id];
>>> @@ -2087,7 +2094,7 @@ static void sas_rediscover(struct domain_device
>>> *dev, const int phy_id)
>>> break;
>>> }
>>> }
>>> - res = sas_rediscover_dev(dev, phy_id, last);
>>> + res = sas_unregister(dev, phy_id, last, retry);
>>> } else
>>> res = sas_discover_new(dev, phy_id);
>>>
>>> @@ -2098,13 +2105,14 @@ static void sas_rediscover(struct
>>> domain_device *dev, const int phy_id)
>>> /**
>>> * sas_ex_revalidate_domain - revalidate the domain
>>> * @port_dev: port domain device.
>>> + * @retry: do we need to revalidate again
>>> *
>>> * NOTE: this process _must_ quit (return) as soon as any connection
>>> * errors are encountered. Connection recovery is done elsewhere.
>>> * Discover process only interrogates devices in order to discover the
>>> * domain.
>>> */
>>> -void sas_ex_revalidate_domain(struct domain_device *port_dev)
>>> +void sas_ex_revalidate_domain(struct domain_device *port_dev, bool
>>> *retry)
>>> {
>>> int res;
>>> struct domain_device *dev = NULL;
>>> @@ -2119,7 +2127,7 @@ void sas_ex_revalidate_domain(struct
>>> domain_device *port_dev)
>>> res = sas_find_bcast_phy(dev, &phy_id, i, true);
>>> if (phy_id == -1)
>>> break;
>>> - sas_rediscover(dev, phy_id);
>>> + sas_rediscover(dev, phy_id, retry);
>>> i = phy_id + 1;
>>> } while (i < ex->num_phys);
>>> }
>>> diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
>>> index e557bcb0c266..deb75765e555 100644
>>> --- a/include/scsi/libsas.h
>>> +++ b/include/scsi/libsas.h
>>> @@ -692,7 +692,7 @@ int sas_discover_root_expander(struct
>>> domain_device *);
>>>
>>> void sas_init_ex_attr(void);
>>>
>>> -void sas_ex_revalidate_domain(struct domain_device *);
>>> +void sas_ex_revalidate_domain(struct domain_device *port_dev, bool
>>> *retry);
>>>
>>> void sas_unregister_domain_devices(struct asd_sas_port *port, int
>>> gone);
>>> void sas_init_disc(struct sas_discovery *disc, struct asd_sas_port *);
>>>
>>
>>
>>
>> .
>>
>
>
> .
>
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