scsi: libsas: Add linkrate and sas_addr change detection in rediscover

Introduce sas_dev_is_flutter() and sas_rediscover_ex_phy() to improve
flutter and device replace detection during rediscovery.

sas_dev_is_flutter() calls sas_ex_phy_discover() before looking up the
child device via sas_ex_phy_to_dev(), ensuring the PHY state is always
updated and avoiding use-after-free since the child device pointer is
obtained after the sleeping SMP request completes.

Add validation for linkrate and sas_addr changes. When the SAS address
changes, phy->attached_sas_addr is restored to the original address
before returning false, so sas_unregister_devs_sas_addr() can properly
match and unregister the old device. The sas_addr check is ordered
before the linkrate check to avoid skipping the restoration when both
change simultaneously.

sas_rediscover_ex_phy() uses the async discovery pattern
(sas_discover_event) instead of the synchronous sas_discover_new() to
ensure proper ordering between device unregistration and rediscovery,
avoiding sysfs_warn_dup() errors.

Signed-off-by: Xingui Yang <yangxingui@huawei.com>
Suggested-by: John Garry <john.g.garry@oracle.com>
Link: https://patch.msgid.link/20260811040334.4184911-3-yangxingui@huawei.com
Signed-off-by: Martin K. Petersen (Oracle) <mkp@kernel.org>

0 files changed, 0 insertions, 0 deletions