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Merge patch series "libsas: rediscover improvements for linkrate/sas_addr"

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Xingui Yang <yangxingui@huawei.com> says:

When a device attached to an expander phy experiences a linkrate change
(e.g., due to cable reconnection or negotiation), the current code in
sas_rediscover_dev() treats it as "broadcast flutter" and takes no action
if the SAS address and device type remain unchanged.

This series is based on John Garry's suggestion [1] to check the linkrate
and mark the device as gone and rediscover when flutter occurs, replacing
the previous v2 patch series that used lldd callbacks.

The previous v2 approach added lldd_dev_info_update callback which John
commented as "seem fragile and too specialized" [2]. This series adopts
a simpler approach that directly checks linkrate/sas_addr changes in
sas_rediscover_dev() and triggers rediscovery using libsas's standard
async discovery pattern.

This aligns with Jason Yan's earlier work [3] which was verified to
solve the linkrate change issue.

Additionally, per the discussion in v3 [4], the existing replace code
path also suffers from the same sysfs duplication issue:
sas_unregister_devs_sas_addr() only marks the device as gone, but the
actual sysfs cleanup happens later in sas_destruct_devices(). Calling
sas_discover_new() immediately after unregister causes sysfs_warn_dup()
errors. This series also optimizes the replace path to use the async
pattern, ensuring proper ordering for both flutter and replace cases.

[1] https://lore.kernel.org/linux-scsi/c4e4c99f-a13c-4e28-8650-48be1f96d7cf@oracle.com/
[2] https://lore.kernel.org/linux-scsi/28bd9d5b-f597-0aae-5340-bd951b2083aa@huawei.com/
[3] https://lore.kernel.org/linux-scsi/20190130082412.9357-6-yanaijie@huawei.com/
[4] https://lore.kernel.org/linux-scsi/b99cd59f-b986-432e-aaf1-3b757e1c4c34@oracle.com/
[5] https://lore.kernel.org/linux-scsi/11581a25-caa6-4ea3-9aa0-2a4dacb7f34e@oracle.com/
[6] https://lore.kernel.org/linux-scsi/20260624063230.3264029-1-yangxingui@huawei.com/

Link: https://patch.msgid.link/20260811040334.4184911-1-yangxingui@huawei.com
Signed-off-by: Martin K. Petersen (Oracle) <mkp@kernel.org>
This commit is contained in:
Martin K. Petersen (Oracle) 2026-08-13 21:55:24 -04:00
commit dc1b802f8e
2 changed files with 80 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

98
drivers/scsi/libsas/sas_expander.c
View File

@ -345,11 +345,10 @@ static void sas_set_ex_phy(struct domain_device *dev, int phy_id,
SAS_ADDR(phy->attached_sas_addr), type);
}
/* check if we have an existing attached ata device on this expander phy */
struct domain_device *sas_ex_to_ata(struct domain_device *ex_dev, int phy_id)
/* Return the domain device attached to an expander phy */
struct domain_device *sas_ex_phy_to_dev(struct domain_device *ex_dev, int phy_id)
{
struct ex_phy *ex_phy = &ex_dev->ex_dev.ex_phy[phy_id];
struct domain_device *dev;
struct sas_rphy *rphy;
if (!ex_phy->port)
@ -359,7 +358,13 @@ struct domain_device *sas_ex_to_ata(struct domain_device *ex_dev, int phy_id)
if (!rphy)
return NULL;
dev = sas_find_dev_by_rphy(rphy);
return sas_find_dev_by_rphy(rphy);
}
/* Check if we have an existing attached ata device on this expander phy */
struct domain_device *sas_ex_to_ata(struct domain_device *ex_dev, int phy_id)
{
struct domain_device *dev = sas_ex_phy_to_dev(ex_dev, phy_id);
if (dev && dev_is_sata(dev))
return dev;
@ -1958,6 +1963,72 @@ static bool dev_type_flutter(enum sas_device_type new, enum sas_device_type old)
return false;
}
static void sas_rediscover_ex_phy(struct domain_device *dev, int phy_id,
bool last)
{
struct expander_device *ex = &dev->ex_dev;
struct ex_phy *phy = &ex->ex_phy[phy_id];
phy->phy_change_count = -1;
ex->ex_change_count = -1;
sas_unregister_devs_sas_addr(dev, phy_id, last);
sas_discover_event(dev->port, DISCE_REVALIDATE_DOMAIN);
}
static bool sas_dev_is_flutter(struct domain_device *dev, int phy_id,
u8 *sas_addr, enum sas_device_type type)
{
struct expander_device *ex = &dev->ex_dev;
struct ex_phy *phy = &ex->ex_phy[phy_id];
struct domain_device *child_dev;
char *action = "";
int res;
if (SAS_ADDR(sas_addr) != SAS_ADDR(phy->attached_sas_addr) ||
!dev_type_flutter(type, phy->attached_dev_type))
return false;
res = sas_ex_phy_discover(dev, phy_id);
if (res)
return false;
child_dev = sas_ex_phy_to_dev(dev, phy_id);
if (!child_dev)
goto out;
if (dev_is_sata(child_dev) &&
phy->attached_dev_type == SAS_SATA_PENDING) {
action = ", needs recovery";
goto out;
}
if (SAS_ADDR(child_dev->sas_addr) != SAS_ADDR(phy->attached_sas_addr)) {
pr_info("ex %016llx phy%02d sas_addr changed from %016llx to %016llx\n",
SAS_ADDR(dev->sas_addr), phy_id,
SAS_ADDR(child_dev->sas_addr),
SAS_ADDR(phy->attached_sas_addr));
/*
* Device unregistering relies on address matching. Restore
* attached_sas_addr back to the original address so that the old
* device can be unregistered later
*/
memcpy(phy->attached_sas_addr, child_dev->sas_addr, SAS_ADDR_SIZE);
return false;
}
if (child_dev->linkrate != phy->linkrate) {
pr_info("ex %016llx phy%02d linkrate changed from %d to %d\n",
SAS_ADDR(dev->sas_addr), phy_id,
child_dev->linkrate, phy->linkrate);
return false;
}
out:
pr_debug("ex %016llx phy%02d broadcast flutter%s\n",
SAS_ADDR(dev->sas_addr), phy_id, action);
return true;
}
static int sas_rediscover_dev(struct domain_device *dev, int phy_id,
bool last, int sibling)
{
@ -2011,27 +2082,16 @@ static int sas_rediscover_dev(struct domain_device *dev, int phy_id,
if (res == 0)
sas_set_ex_phy(dev, phy_id, disc_resp);
goto out_free_resp;
} else if (SAS_ADDR(sas_addr) == SAS_ADDR(phy->attached_sas_addr) &&
dev_type_flutter(type, phy->attached_dev_type)) {
struct domain_device *ata_dev = sas_ex_to_ata(dev, phy_id);
char *action = "";
sas_ex_phy_discover(dev, phy_id);
if (ata_dev && phy->attached_dev_type == SAS_SATA_PENDING)
action = ", needs recovery";
pr_debug("ex %016llx phy%02d broadcast flutter%s\n",
SAS_ADDR(dev->sas_addr), phy_id, action);
goto out_free_resp;
}
if (sas_dev_is_flutter(dev, phy_id, sas_addr, type))
goto out_free_resp;
/* we always have to delete the old device when we went here */
pr_info("ex %016llx phy%02d replace %016llx\n",
SAS_ADDR(dev->sas_addr), phy_id,
SAS_ADDR(phy->attached_sas_addr));
sas_unregister_devs_sas_addr(dev, phy_id, last);
res = sas_discover_new(dev, phy_id);
sas_rediscover_ex_phy(dev, phy_id, last);
out_free_resp:
kfree(disc_resp);
return res;

1
drivers/scsi/libsas/sas_internal.h
View File

@ -91,6 +91,7 @@ int sas_smp_get_phy_events(struct sas_phy *phy);
void sas_device_set_phy(struct domain_device *dev, struct sas_port *port);
struct domain_device *sas_find_dev_by_rphy(struct sas_rphy *rphy);
struct domain_device *sas_ex_phy_to_dev(struct domain_device *ex_dev, int phy_id);
struct domain_device *sas_ex_to_ata(struct domain_device *ex_dev, int phy_id);
int sas_ex_phy_discover(struct domain_device *dev, int single);
int sas_get_report_phy_sata(struct domain_device *dev, int phy_id,