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SubjectRe: [PATCH v4] scsi: libsas: Fix the failure of adding phy with zero-address to port
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On 24/11/2023 02:27, yangxingui wrote:
>> We already do this in sas_ex_join_wide_port(), right?
> No, If the addr of ex_phy matches dev->parent, sas_ex_join_wide_port()
> will not be called, but sas_add_parent_port() will be called  as follows:
> static int sas_ex_discover_dev(struct domain_device *dev, int phy_id)
> {
>         struct expander_device *ex = &dev->ex_dev;
>         struct ex_phy *ex_phy = &ex->ex_phy[phy_id];
>         struct domain_device *child = NULL;
>         int res = 0;
>
>     <...>
>         /* Parent and domain coherency */
>         if (!dev->parent && sas_phy_match_port_addr(dev->port, ex_phy)) {
>                 sas_add_parent_port(dev, phy_id);
>                 return 0;
>         }
>         if (dev->parent && sas_phy_match_dev_addr(dev->parent, ex_phy)) {
>                 sas_add_parent_port(dev, phy_id);
>                 if (ex_phy->routing_attr == TABLE_ROUTING)
>                         sas_configure_phy(dev, phy_id,
> dev->port->sas_addr, 1);
>                 return 0;
>         }
>     <...>
> }
>
>>
>> I am not saying that what we do now does not have a problem - I am
>> just trying to understand what currently happens
>
> ok, because ex_phy->port is not set when calling sas_add_parent_port(),
> when deleting phy from the parent wide port, it is not removed from the
> phy_list of the parent wide port as follows:
> static void sas_unregister_devs_sas_addr(struct domain_device *parent,
>                                          int phy_id, bool last)
> {
>     <...>
>     // Since ex_phy->port is not set, this branch will not be enter

But then how does this ever work? It is because we follow path
sas_rediscover_dev() -> sas_discover_new() -> sas_ex_discover_devices()
-> sas_ex_discover_dev() -> sas_add_parent_port(), and not
sas_rediscover_dev() -> sas_discover_new() -> sas_ex_join_wide_port()?
If so, is that because ephy->sas_attached_phy == 0 in sas_discover_new()
-> sas_ex_join_wide_port() and it fails?

BTW, about something mentioned earlier - adding the phy19 with SAS_ADDR
= 0 ever to a sas_port seems wrong.

>         if (phy->port) {
>                 sas_port_delete_phy(phy->port, phy->phy);
>                 sas_device_set_phy(found, phy->port);
>                 if (phy->port->num_phys == 0) {
>                         list_add_tail(&phy->port->del_list,
>                                 &parent->port->sas_port_del_list);
>                         if (ex_dev->parent_port == phy->port)
>                                 ex_dev->parent_port = NULL;
>                 }
>                 phy->port = NULL;
>         }
> }

Thanks,
John

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