dibs: Create class dibs

Create '/sys/class/dibs' to represent multiple kinds of dibs devices in
sysfs. Show s390/ism devices as well as dibs_loopback devices.

Show attribute fabric_id using dibs_ops.get_fabric_id(). This can help
users understand which dibs devices are connected to the same fabric in
different systems and which dibs devices are loopback devices
(fabric_id 0xffff)

Instead of using the same name as the pci device, give the ism devices
their own readable names based on uid or fid from the HW definition.

smc_loopback was never visible in sysfs. dibs_loopback is now represented
as a virtual device.

For the SMC feature "software defined pnet-id" either the ib device name or
the PCI-ID (actually the parent device name) can be used for SMC-R entries.
Mimic this behaviour for SMC-D, and check the parent device name as well.
So device name or PCI-ID can be used for ism and device name can be used
for dibs-loopback. Note that this:
IB_DEVICE_NAME_MAX - 1 == smc_pnet_policy.[SMC_PNETID_IBNAME].len
is the length of smcd_name. Future SW-pnetid cleanup patches to could use a
meaningful define, but that would touch too much unrelated code here.

Examples:
---------
ism before:
> ls /sys/bus/pci/devices/0000:00:00.0/0000:00:00.0
uevent

ism now:
> ls /sys/bus/pci/devices/0000:00:00.0/dibs/ism30
device -> ../../../0000:00:00.0/
fabric_id
subsystem -> ../../../../../class/dibs/
uevent

dibs loopback:
> ls /sys/devices/virtual/dibs/lo/
fabric_id
subsystem -> ../../../../class/dibs/
uevent

dibs class:
> ls -l /sys/class/dibs/
ism30 -> ../../devices/pci0000:00/0000:00:00.0/dibs/ism30/
lo -> ../../devices/virtual/dibs/lo/

For comparison:
> ls -l /sys/class/net/
enc8410 -> ../../devices/qeth/0.0.8410/net/enc8410/
ens1693 -> ../../devices/pci0001:00/0001:00:00.0/net/ens1693/
lo -> ../../devices/virtual/net/lo/

Signed-off-by: Julian Ruess <julianr@linux.ibm.com>
Co-developed-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Link: https://patch.msgid.link/20250918110500.1731261-10-wintera@linux.ibm.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/net/smc/smc_pnet.c b/net/smc/smc_pnet.c
index d0df7f2b03aa..a3a1e1fde8eb 100644
--- a/net/smc/smc_pnet.c
+++ b/net/smc/smc_pnet.c
@@ -332,8 +332,11 @@ static struct smcd_dev *smc_pnet_find_smcd(char *smcd_name)
 
 	mutex_lock(&smcd_dev_list.mutex);
 	list_for_each_entry(smcd_dev, &smcd_dev_list.list, list) {
-		if (!strncmp(dev_name(&smcd_dev->dibs->dev),
-			     smcd_name, IB_DEVICE_NAME_MAX - 1))
+		if (!strncmp(dev_name(&smcd_dev->dibs->dev), smcd_name,
+			     IB_DEVICE_NAME_MAX - 1) ||
+		    (smcd_dev->dibs->dev.parent &&
+		     !strncmp(dev_name(smcd_dev->dibs->dev.parent), smcd_name,
+			      IB_DEVICE_NAME_MAX - 1)))
 			goto out;
 	}
 	smcd_dev = NULL;
@@ -1190,7 +1193,6 @@ int smc_pnetid_by_table_ib(struct smc_ib_device *smcibdev, u8 ib_port)
  */
 int smc_pnetid_by_table_smcd(struct smcd_dev *smcddev)
 {
-	const char *ib_name = dev_name(&smcddev->dibs->dev);
 	struct smc_pnettable *pnettable;
 	struct smc_pnetentry *tmp_pe;
 	struct smc_net *sn;
@@ -1203,7 +1205,13 @@ int smc_pnetid_by_table_smcd(struct smcd_dev *smcddev)
 	mutex_lock(&pnettable->lock);
 	list_for_each_entry(tmp_pe, &pnettable->pnetlist, list) {
 		if (tmp_pe->type == SMC_PNET_IB &&
-		    !strncmp(tmp_pe->ib_name, ib_name, IB_DEVICE_NAME_MAX)) {
+		    (!strncmp(tmp_pe->ib_name,
+			       dev_name(&smcddev->dibs->dev),
+			       sizeof(tmp_pe->ib_name)) ||
+		     (smcddev->dibs->dev.parent &&
+		      !strncmp(tmp_pe->ib_name,
+			       dev_name(smcddev->dibs->dev.parent),
+			       sizeof(tmp_pe->ib_name))))) {
 			smc_pnet_apply_smcd(smcddev, tmp_pe->pnet_name);
 			rc = 0;
 			break;