Re: [PATCH v3 2/2] scsi: libsas: Add linkrate and sas_addr change detection in rediscover
From: yangxingui
Date: Wed May 27 2026 - 22:50:02 EST
On 2026/5/27 17:42, John Garry wrote:
On 25/05/2026 03:25, yangxingui wrote:Yes, it can recreate, such as quickly replacing a disk or swapping two disk. However, during normal use, we recommend that customers wait for one minute before inserting a new disk when replacing a disk to avoid this issue.
Hi, John
Hi, John
As the commit log. The existing pattern (unregister + sas_discover_new) handles the "replace" case where the SAS address changes completely, implying a different device.
For the flutter case where we detect linkrate/sas_addr changes,
Can you please clarify this: you say that the existing pattern handles "replace" case where the SAS address changes completely, and then flutter case covers sas_addr changes.
What is the difference in the SAS address changes between the two cases?
The difference is in when the SAS address change is detected:
Replace case:
- Detected immediately by the initial SMP DISCOVER response
- New SAS address differs from stored phy->attached_sas_addr
Flutter case:
- Initial SMP DISCOVER shows SAS address matching stored phy- >attached_sas_addr
- Linkrate may change
- After sas_ex_phy_discover() refreshes phy info, child device address and linkrate may mismatched with refreshed phy info
Additional issue with Replace flow:
The existing replace code path also suffers from the same sysfs_warn_dup issue I mentioned earlier. sas_unregister_devs_sas_addr() only marks the device as gone and adds it to destroy_list. The actual sysfs cleanup happens later in sas_destruct_devices(). Calling sas_discover_new() immediately after unregister causes sysfs duplicate directory errors.
So can you actually recreate this issue? Or is it just theoretical?
The following are example of similar exception logs:
log1：
[ 7957.283194][T67794] sas: ex 500e004aaaaaaa1f phy19 replace 5001882016000000
[ 7957.290960][T67794] sysfs: cannot create duplicate filename '/devices/pci0000:74/0000:74:02.0/host1/port-1:2/expander-1:2/port-1:2:19'
[ 7957.317973][T67794] Hardware name: Huawei Technologies Co., Ltd. EVBCS/EVBCS, BIOS CS B055 2P TA 02/19/2020
[ 7957.328900][T67794] Workqueue: 0000:74:02.0_disco_q sas_revalidate_domain [libsas]
[ 7957.337636][T67794] Call trace:
[ 7957.341419][T67794] dump_backtrace+0x0/0x200
[ 7957.346317][T67794] show_stack+0x20/0x30
[ 7957.350887][T67794] dump_stack+0xf0/0x138
[ 7957.355511][T67794] sysfs_warn_dup+0x6c/0x90
[ 7957.360410][T67794] sysfs_create_dir_ns+0xf8/0x11c
[ 7957.365795][T67794] create_dir+0x30/0x18c
[ 7957.370416][T67794] kobject_add_internal+0x5c/0x190
[ 7957.375877][T67794] kobject_add+0x98/0x110
[ 7957.380566][T67794] device_add+0x100/0x4a0
[ 7957.385255][T67794] sas_port_add+0x30/0x74 [scsi_transport_sas]
[ 7957.391722][T67794] sas_ex_discover_end_dev+0x328/0x630 [libsas]
[ 7957.398328][T67794] sas_ex_discover_dev+0x230/0x320 [libsas]
[ 7957.404599][T67794] sas_ex_discover_devices+0x60/0x100 [libsas]
[ 7957.411116][T67794] sas_discover_new+0xa4/0x150 [libsas]
[ 7957.416986][T67794] sas_rediscover_dev+0x198/0x260 [libsas]
[ 7957.423125][T67794] sas_rediscover+0xb8/0x100 [libsas]
[ 7957.428854][T67794] sas_ex_revalidate_domain+0x5c/0xe0 [libsas]
[ 7957.435320][T67794] sas_revalidate_domain+0x1ac/0x1b4 [libsas]
[ 7957.441714][T67794] process_one_work+0x1d8/0x4cc
[ 7957.446884][T67794] worker_thread+0x158/0x410
[ 7957.451769][T67794] kthread+0x108/0x13c
[ 7957.456089][T67794] ret_from_fork+0x10/0x18
[ 7957.460800][T67794] kobject_add_internal failed for port-1:2:19 with -EEXIST, don't try to register things with the same name in the same directory.
[ 7957.474864][T67794] sas: ex 500e004aaaaaaa1f phy19 failed to discover
log2：
[ 8608.766031][T66335] sas: ex 500e004aaaaaaa1f phy17 change count has changed
[ 8608.774390][T66335] sysfs: cannot create duplicate filename '/devices/pci0000:74/0000:74:02.0/host1/port-1:2/expander-1:3/port-1:3:17'
[ 8608.800667][T66335] Hardware name: Huawei Technologies Co., Ltd. EVBCS/EVBCS, BIOS CS B055 2P TA 02/19/2020
[ 8608.811270][T66335] Workqueue: 0000:74:02.0_disco_q sas_revalidate_domain [libsas]
[ 8608.819685][T66335] Call trace:
[ 8608.823235][T66335] dump_backtrace+0x0/0x200
[ 8608.827990][T66335] show_stack+0x20/0x30
[ 8608.832387][T66335] dump_stack+0xf0/0x138
[ 8608.836858][T66335] sysfs_warn_dup+0x6c/0x90
[ 8608.841580][T66335] sysfs_create_dir_ns+0xf8/0x11c
[ 8608.846814][T66335] create_dir+0x30/0x18c
[ 8608.851257][T66335] kobject_add_internal+0x5c/0x190
[ 8608.856566][T66335] kobject_add+0x98/0x110
[ 8608.861083][T66335] device_add+0x100/0x4a0
[ 8608.865588][T66335] sas_port_add+0x30/0x74 [scsi_transport_sas]
[ 8608.871919][T66335] sas_ex_discover_end_dev+0x328/0x630 [libsas]
[ 8608.878345][T66335] sas_ex_discover_dev+0x230/0x320 [libsas]
[ 8608.884430][T66335] sas_ex_discover_devices+0x60/0x100 [libsas]
[ 8608.890768][T66335] sas_discover_new+0xa4/0x150 [libsas]
[ 8608.896506][T66335] sas_rediscover+0xd8/0x100 [libsas]
[ 8608.902075][T66335] sas_ex_revalidate_domain+0x5c/0xe0 [libsas]
[ 8608.908438][T66335] sas_revalidate_domain+0x1ac/0x1b4 [libsas]
[ 8608.914708][T66335] process_one_work+0x1d8/0x4cc
[ 8608.919757][T66335] worker_thread+0x158/0x410
[ 8608.924533][T66335] kthread+0x108/0x13c
[ 8608.928778][T66335] ret_from_fork+0x10/0x18
[ 8608.933377][T66335] kobject_add_internal failed for port-1:3:17 with -EEXIST, don't try to register things with the same name in the same directory.
[ 8608.947364][T66335] sas: ex 500e004aaaaaaa1f phy17 failed to discover
About this following code:
+ if (need_rediscover) {
+ set_bit(SAS_DEV_GONE, &child_dev->state);
+ phy->phy_change_count = -1;
+ ex->ex_change_count = -1;
+ sas_unregister_devs_sas_addr(dev, phy_id, true);
+ sas_discover_event(dev->port, DISCE_REVALIDATE_DOMAIN);
+ } else {
Can we factor it out with other code? AFAICR, this can pattern can be seen elsewhere.
Yes, in the updated v4 version, I refined it into a function.
In the v4 test log, the disk is gone and then connected again.
test case:
phy=phy-10:0:0
echo 1.5 Gbit > /sys/class/sas_phy/$phy/maximum_linkrate
The details are as follows:
[ 541.880156] sas: broadcast received: 0
[ 541.880712] sas: REVALIDATING DOMAIN on port 0, pid:8995
[ 541.882509] sas: ex 500e004aaaaaaa1f phy00 change count has changed
[ 541.883680] sas: ex 500e004aaaaaaa1f phy00 originated BROADCAST(CHANGE)
[ 541.883703] sas: ex 500e004aaaaaaa1f rediscovering phy00
[ 541.884838] sas: ex 500e004aaaaaaa1f phy00:U:8 attached: 500e004aaaaaaa00 (stp pending)
[ 541.884844] sas: ex 500e004aaaaaaa1f phy00 broadcast flutter, needs recovery
[ 541.898893] sas: done REVALIDATING DOMAIN on port 0, pid:8995, res 0x0
[ 541.899444] sas: broadcast received: 0
[ 541.899506] sas: REVALIDATING DOMAIN on port 0, pid:8995
[ 541.899659] sas: done REVALIDATING DOMAIN on port 0, pid:8995, res 0x0
[ 541.900213] sas: broadcast received: 0
[ 541.900282] sas: REVALIDATING DOMAIN on port 0, pid:8995
[ 541.900367] sas: done REVALIDATING DOMAIN on port 0, pid:8995, res 0x0
[ 541.900992] sas: broadcast received: 0
[ 541.901041] sas: REVALIDATING DOMAIN on port 0, pid:8995
[ 541.901132] sas: done REVALIDATING DOMAIN on port 0, pid:8995, res 0x0
[ 541.901160] sas: broadcast received: 0
[ 541.901195] sas: REVALIDATING DOMAIN on port 0, pid:8995
[ 541.901278] sas: done REVALIDATING DOMAIN on port 0, pid:8995, res 0x0
[ 541.901887] sas: broadcast received: 0
[ 541.901948] sas: REVALIDATING DOMAIN on port 0, pid:8995
[ 541.902035] sas: done REVALIDATING DOMAIN on port 0, pid:8995, res 0x0
[ 541.902673] sas: broadcast received: 0
[ 541.902741] sas: REVALIDATING DOMAIN on port 0, pid:8995
[ 541.902836] sas: done REVALIDATING DOMAIN on port 0, pid:8995, res 0x0
[ 541.903467] sas: broadcast received: 0
[ 541.903536] sas: REVALIDATING DOMAIN on port 0, pid:8995
[ 541.903625] sas: done REVALIDATING DOMAIN on port 0, pid:8995, res 0x0
[ 541.919967] sas: broadcast received: 0
[ 541.920036] sas: REVALIDATING DOMAIN on port 0, pid:8995
[ 541.920385] sas: ex 500e004aaaaaaa1f phy00 change count has changed
[ 541.920494] sas: ex 500e004aaaaaaa1f phy00 originated BROADCAST(CHANGE)
[ 541.920504] sas: ex 500e004aaaaaaa1f rediscovering phy00
[ 541.920687] sas: ex 500e004aaaaaaa1f phy00:U:8 attached: 500e004aaaaaaa00 (stp)
[ 541.920697] sas: ex 500e004aaaaaaa1f phy00 linkrate changed from 9 to 8
[ 541.920710] sas: ex 500e004aaaaaaa1f phy00 replace 500e004aaaaaaa00
[ 541.922648] sas: done REVALIDATING DOMAIN on port 0, pid:8995, res 0x0
[ 542.007031] sd 10:0:0:0: [sdd] Stopping disk
[ 542.007122] sd 10:0:0:0: [sdd] Start/Stop Unit failed: Result: hostbyte=0x04 driverbyte=DRIVER_OK
[ 542.027347] hisi_sas_v3_hw 0000:70:04.0: dev[2:5] is gone
[ 542.039000] sas: REVALIDATING DOMAIN on port 0, pid:8995
[ 542.039358] sas: ex 500e004aaaaaaa1f phy00 change count has changed
[ 542.039436] sas: broadcast received: 0
[ 542.039470] sas: ex 500e004aaaaaaa1f phy00 originated BROADCAST(CHANGE)
[ 542.039482] sas: ex 500e004aaaaaaa1f phy00 new device attached
[ 542.039569] sas: ex 500e004aaaaaaa1f phy00:U:8 attached: 500e004aaaaaaa00 (stp)
[ 542.040152] hisi_sas_v3_hw 0000:70:04.0: dev[15:5] found
[ 542.042112] sas: done REVALIDATING DOMAIN on port 0, pid:8995, res 0x0
[ 542.153137] sas: Enter sas_scsi_recover_host busy: 0 failed: 0
[ 542.153900] sas: ata10: end_device-10:0:1: dev error handler
[ 542.153972] sas: ata11: end_device-10:0:2: dev error handler
[ 542.153994] sas: ata12: end_device-10:0:5: dev error handler
[ 542.154010] sas: ata13: end_device-10:0:6: dev error handler
[ 542.154021] sas: ata14: end_device-10:0:9: dev error handler
[ 542.154032] sas: ata15: end_device-10:0:10: dev error handler
[ 542.154044] sas: ata9: end_device-10:0:0: dev error handler
[ 542.519243] ata9.00: ATA-10: ST4000NM0035-1V4107, TN03, max UDMA/133
[ 542.522538] ata9.00: 7814037168 sectors, multi 0: LBA48 NCQ (depth 32)
[ 542.522561] ata9.00: Features: DIPM NCQ-sndrcv
[ 542.527315] ata9.00: configured for UDMA/133
[ 542.527976] sas: --- Exit sas_scsi_recover_host: busy: 0 failed: 0 tries: 1
[ 542.570193] scsi 10:0:13:0: Direct-Access ATA ST4000NM0035-1V4 TN03 PQ: 0 ANSI: 5
[ 542.571771] scsi 10:0:13:0: Attached scsi generic sg3 type 0
Thanks,
Xingui