[systemd-devel] [PATCH 2/2] udev/path_id: improve and enhance bus detection for Linux on z Systems

[Hendrik Brueckner]

From: Liu Yuan Yuan <bjyyliu at linux.vnet.ibm.com>

Improve and enhance the path_id udev builtin to correctly handle bus'
available on Linux on z Systems (s390).

Previously, the CCW bus and, in particular, any FCP devices on it, have
been treated separately.  This commit integrates the CCW bus into the
device chain loop.  FCP devices and their associated SCSI disks are now
handled through the common SCSI handling functions in path_id.

This implies also a change in the naming of the symbolic links created
by udev.  So any backports of this commit to existing Linux distribution
must be done with care.  If a backport is requires, a udev rule can be
created to create the "old-style" symbolic links too.

Apart from the CCW bus, this commit adds bus support for the:

- ccwgroup bus which manages network devices, and
- ap bus which manages cryptographic adapters
- iucv bus which manages IUCV devices on z/VM

Signed-off-by: Liu Yuan Yuan <bjyyliu at linux.vnet.ibm.com>
Signed-off-by: Hendrik Brueckner <brueckner at linux.vnet.ibm.com>
---
 src/udev/udev-builtin-path_id.c |   57 ++++++++++++++++++++------------------
 1 files changed, 30 insertions(+), 27 deletions(-)

diff --git a/src/udev/udev-builtin-path_id.c b/src/udev/udev-builtin-path_id.c
index 01e2c65..a436e4f 100644
--- a/src/udev/udev-builtin-path_id.c
+++ b/src/udev/udev-builtin-path_id.c
@@ -591,31 +591,23 @@ static struct udev_device *handle_bcma(struct udev_device *parent, char **path)
         return parent;
 }
 
-static struct udev_device *handle_ccw(struct udev_device *parent, struct udev_device *dev, char **path) {
-        struct udev_device *scsi_dev;
+/* Handle devices of AP bus in System z platform. */
+static struct udev_device *handle_ap(struct udev_device *parent, char **path) {
+        const char *type, *func;
 
         assert(parent);
-        assert(dev);
         assert(path);
 
-        scsi_dev = udev_device_get_parent_with_subsystem_devtype(dev, "scsi", "scsi_device");
-        if (scsi_dev != NULL) {
-                const char *wwpn;
-                const char *lun;
-                const char *hba_id;
-
-                hba_id = udev_device_get_sysattr_value(scsi_dev, "hba_id");
-                wwpn = udev_device_get_sysattr_value(scsi_dev, "wwpn");
-                lun = udev_device_get_sysattr_value(scsi_dev, "fcp_lun");
-                if (hba_id != NULL && lun != NULL && wwpn != NULL) {
-                        path_prepend(path, "ccw-%s-zfcp-%s:%s", hba_id, wwpn, lun);
-                        goto out;
-                }
-        }
+        type = udev_device_get_sysattr_value(parent, "type");
+        func = udev_device_get_sysattr_value(parent, "ap_functions");
 
-        path_prepend(path, "ccw-%s", udev_device_get_sysname(parent));
+        if (type != NULL && func != NULL) {
+                path_prepend(path, "ap-%s-%s", type, func);
+                goto out;
+        }
+        path_prepend(path, "ap-%s", udev_device_get_sysname(parent));
 out:
-        parent = skip_subsystem(parent, "ccw");
+        parent = skip_subsystem(parent, "ap");
         return parent;
 }
 
@@ -627,13 +619,6 @@ static int builtin_path_id(struct udev_device *dev, int argc, char *argv[], bool
 
         assert(dev);
 
-        /* S390 ccw bus */
-        parent = udev_device_get_parent_with_subsystem_devtype(dev, "ccw", NULL);
-        if (parent != NULL) {
-                handle_ccw(parent, dev, &path);
-                goto out;
-        }
-
         /* walk up the chain of devices and compose path */
         parent = dev;
         while (parent != NULL) {
@@ -681,6 +666,25 @@ static int builtin_path_id(struct udev_device *dev, int argc, char *argv[], bool
                         parent = skip_subsystem(parent, "scm");
                         supported_transport = true;
                         supported_parent = true;
+                } else if (streq(subsys, "ccw")) {
+                        path_prepend(&path, "ccw-%s", udev_device_get_sysname(parent));
+                        parent = skip_subsystem(parent, "ccw");
+                        supported_transport = true;
+                        supported_parent = true;
+                } else if (streq(subsys, "ccwgroup")) {
+                        path_prepend(&path, "ccwgroup-%s", udev_device_get_sysname(parent));
+                        parent = skip_subsystem(parent, "ccwgroup");
+                        supported_transport = true;
+                        supported_parent = true;
+                } else if (streq(subsys, "ap")) {
+                        parent = handle_ap(parent, &path);
+                        supported_transport = true;
+                        supported_parent = true;
+                } else if (streq(subsys, "iucv")) {
+                        path_prepend(&path, "iucv-%s", udev_device_get_sysname(parent));
+                        parent = skip_subsystem(parent, "iucv");
+                        supported_transport = true;
+                        supported_parent = true;
                 }
 
                 if (parent)
@@ -703,7 +707,6 @@ static int builtin_path_id(struct udev_device *dev, int argc, char *argv[], bool
         if (streq(udev_device_get_subsystem(dev), "block") && !supported_transport)
                 path = mfree(path);
 
-out:
         if (path != NULL) {
                 char tag[UTIL_NAME_SIZE];
                 size_t i;
-- 
1.7.1