Re: [PATCH v3] scsi: core: Add 'serial' sysfs attribute for SCSI/SATA
From: Hannes Reinecke
Date: Wed Feb 18 2026 - 03:28:39 EST
On 2/17/26 17:58, Igor Pylypiv wrote:
On Tue, Feb 10, 2026 at 08:51:24AM -0800, Igor Pylypiv wrote:Hmm. Okay, sounds reasonable.
On Tue, Feb 10, 2026 at 12:38:51PM +0100, Hannes Reinecke wrote:
On 2/9/26 22:21, Igor Pylypiv wrote:
Add a 'serial' sysfs attribute for SCSI and SATA devices. This attribute
exposes the Unit Serial Number, which is derived from the Device
Identification Vital Product Data (VPD) page 0x80.
Whitespace is stripped from the retrieved serial number to handle
the different alignment (right-aligned for SCSI, potentially
left-aligned for SATA). As noted in SAT-5 10.5.3, "Although SPC-5 defines
the PRODUCT SERIAL NUMBER field as right-aligned, ACS-5 does not require
its SERIAL NUMBER field to be right-aligned. Therefore, right-alignment
of the PRODUCT SERIAL NUMBER field for the translation is not assured."
This attribute is used by tools such as lsblk to display the serial
number of block devices.
Signed-off-by: Igor Pylypiv <ipylypiv@xxxxxxxxxx>
---
v2->v3 changes:
- Replaced sysfs_emit(buf, "%s\n", buf) with a manual newline placement
to avoid undefined behavior of passing the output buffer as an input.
v1->v2 changes:
- Reordered declarations in scsi_vpd_lun_serial() from longest to shortest.
- Replaced rcu_read_lock()/rcu_read_unlock() with guard(rcu)().
drivers/scsi/scsi_lib.c | 47 ++++++++++++++++++++++++++++++++++++++
drivers/scsi/scsi_sysfs.c | 16 +++++++++++++
include/scsi/scsi_device.h | 1 +
3 files changed, 64 insertions(+)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 4a902c9dfd8b..c17fbe4dd845 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -13,6 +13,7 @@
#include <linux/bitops.h>
#include <linux/blkdev.h>
#include <linux/completion.h>
+#include <linux/ctype.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/init.h>
@@ -3459,6 +3460,52 @@ int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)
}
EXPORT_SYMBOL(scsi_vpd_lun_id);
+/**
+ * scsi_vpd_lun_serial - return a unique device serial number
+ * @sdev: SCSI device
+ * @sn: buffer for the serial number
+ * @sn_size: size of the buffer
+ *
+ * Copies the device serial number into @sn based on the information in
+ * the VPD page 0x80 of the device. The string will be null terminated
+ * and have leading and trailing whitespace stripped.
+ *
+ * Returns the length of the serial number or error on failure.
+ */
+int scsi_vpd_lun_serial(struct scsi_device *sdev, char *sn, size_t sn_size)
+{
+ const struct scsi_vpd *vpd_pg80;
+ const unsigned char *d;
+ int len;
+
+ guard(rcu)();
+ vpd_pg80 = rcu_dereference(sdev->vpd_pg80);
+ if (!vpd_pg80)
+ return -ENXIO;
+
+ len = vpd_pg80->len - 4;
+ d = vpd_pg80->data + 4;
+
+ /* Skip leading spaces */
+ while (len > 0 && isspace(*d)) {
+ len--;
+ d++;
+ }
+
+ /* Skip trailing spaces */
+ while (len > 0 && isspace(d[len - 1]))
+ len--;
+
Please use 'strim()' instead.
Hi Hannes,
Bart pointed this out in V1 as well. I'll copy-paste my reply from V1:
"Yes, I considered using strim(). strim() modifies the input buffer by
replacing first trailing whitespace with '\0' so we can't use it directly
on the vpd_pg80->data. The solution would be to copy the whole vpd page
data into the sn buffer and call strim() on the sn buffer. strim() returns
a pointer to the first non-whitespace character so we would also need to
memmove the serial number to the beginning of the sn buffer. All this extra
copying seems to be redundant so I went ahead with a simpler solution
that does a single memcpy()."
Please let me know your thoughts on this.
Hi Hannes,
Ping for a feedback.
Sending this in case my previous reply fell through the cracks.
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@xxxxxxx +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich