From 2e7f41bd0632312d00d472a73a312218a29ce65b Mon Sep 17 00:00:00 2001
From: Viktor Mihajlovski <mihajlov@linux.ibm.com>
Date: Thu, 18 Mar 2021 11:03:34 +0100
Subject: [PATCH] udev: fix slot based network names on s390
The s390 PCI driver assigns the hotplug slot name from the
function_id attribute of the PCI device using a 8 char hexadecimal
format to match the underlying firmware/hypervisor notation.
Further, there's always a one-to-one mapping between a PCI
function and a hotplug slot, as individual functions can
hot plugged even for multi-function devices.
As the generic matching code will always try to parse the slot
name in /sys/bus/pci/slots as a positive decimal number, either
a wrong value might be produced for ID_NET_NAME_SLOT if
the slot name consists of decimal numbers only, or none at all
if a character in the range from 'a' to 'f' is encountered.
Additionally, the generic code assumes that two interfaces
share a hotplug slot, if they differ only in the function part
of the PCI address. E.g., for an interface with the PCI address
dddd:bb:aa.f, it will match the device to the first slot with
an address dddd:bb:aa. As more than one slot may have this address
for the s390 PCI driver, the wrong slot may be selected.
To resolve this we're adding a new naming schema version with the
flag NAMING_SLOT_FUNCTION_ID, which enables the correct matching
of hotplug slots if the device has an attribute named function_id.
The ID_NET_NAME_SLOT property will only be produced if there's
a file /sys/bus/pci/slots/<slotname> where <slotname> matches
the value of /sys/bus/pci/devices/.../function_id in 8 char
hex notation.
Fixes #19016
See also #19078
Related: #1939914
(cherry picked from commit a496a238e8ee66ce25ad13a3f46549b2e2e979fc)
---
man/systemd.net-naming-scheme.xml | 10 +++++++++
src/udev/udev-builtin-net_id.c | 34 +++++++++++++++++++++++++++++++
2 files changed, 44 insertions(+)
diff --git a/man/systemd.net-naming-scheme.xml b/man/systemd.net-naming-scheme.xml
index fe1aa4b654..e42c93eaad 100644
--- a/man/systemd.net-naming-scheme.xml
+++ b/man/systemd.net-naming-scheme.xml
@@ -313,6 +313,16 @@
<para>Same as naming scheme <constant>rhel-8.4</constant>.</para>
</varlistentry>
+ <varlistentry>
+ <term><constant>rhel-8.7</constant></term>
+
+ <listitem><para>PCI hotplug slot names for the s390 PCI driver are a hexadecimal representation
+ of the <filename>function_id</filename> device attribute. This attribute is now used to build the
+ <varname>ID_NET_NAME_SLOT</varname>. Before that, all slot names were parsed as decimal
+ numbers, which could either result in an incorrect value of the <varname>ID_NET_NAME_SLOT</varname>
+ property or none at all.</para></listitem>
+ </varlistentry>
+
<para>Note that <constant>latest</constant> may be used to denote the latest scheme known to this
particular version of systemd.</para>
</variablelist>
diff --git a/src/udev/udev-builtin-net_id.c b/src/udev/udev-builtin-net_id.c
index 386d74ca5e..b57227a09f 100644
--- a/src/udev/udev-builtin-net_id.c
+++ b/src/udev/udev-builtin-net_id.c
@@ -126,6 +126,7 @@ typedef enum NamingSchemeFlags {
NAMING_SR_IOV_V = 1 << 0, /* Use "v" suffix for SR-IOV, see 609948c7043a40008b8299529c978ed8e11de8f6*/
NAMING_NPAR_ARI = 1 << 1, /* Use NPAR "ARI", see 6bc04997b6eab35d1cb9fa73889892702c27be09 */
NAMING_BRIDGE_NO_SLOT = 1 << 9, /* Don't use PCI hotplug slot information if the corresponding device is a PCI bridge */
+ NAMING_SLOT_FUNCTION_ID = 1 << 10, /* Use function_id if present to identify PCI hotplug slots */
/* And now the masks that combine the features above */
NAMING_V238 = 0,
@@ -137,6 +138,7 @@ typedef enum NamingSchemeFlags {
NAMING_RHEL_8_4 = NAMING_V239|NAMING_BRIDGE_NO_SLOT,
NAMING_RHEL_8_5 = NAMING_RHEL_8_4,
NAMING_RHEL_8_6 = NAMING_RHEL_8_4,
+ NAMING_RHEL_8_7 = NAMING_RHEL_8_4|NAMING_SLOT_FUNCTION_ID,
_NAMING_SCHEME_FLAGS_INVALID = -1,
} NamingSchemeFlags;
@@ -156,6 +158,7 @@ static const NamingScheme naming_schemes[] = {
{ "rhel-8.4", NAMING_RHEL_8_4 },
{ "rhel-8.5", NAMING_RHEL_8_5 },
{ "rhel-8.6", NAMING_RHEL_8_6 },
+ { "rhel-8.7", NAMING_RHEL_8_7 },
/* … add more schemes here, as the logic to name devices is updated … */
};
@@ -477,6 +480,37 @@ static int dev_pci_slot(struct udev_device *dev, struct netnames *names) {
hotplug_slot_dev = names->pcidev;
while (hotplug_slot_dev) {
+ if (!udev_device_get_sysname(hotplug_slot_dev))
+ continue;
+
+ /* The <sysname>/function_id attribute is unique to the s390 PCI driver.
+ If present, we know that the slot's directory name for this device is
+ /sys/bus/pci/XXXXXXXX/ where XXXXXXXX is the fixed length 8 hexadecimal
+ character string representation of function_id.
+ Therefore we can short cut here and just check for the existence of
+ the slot directory. As this directory has to exist, we're emitting a
+ debug message for the unlikely case it's not found.
+ Note that the domain part of doesn't belong to the slot name here
+ because there's a 1-to-1 relationship between PCI function and its hotplug
+ slot.
+ */
+ if (naming_scheme_has(NAMING_SLOT_FUNCTION_ID)) {
+ attr = udev_device_get_sysattr_value(hotplug_slot_dev, "function_id");
+ if (attr) {
+ int function_id;
+ _cleanup_free_ char *str;
+
+ if (safe_atoi(attr, &function_id) >= 0 &&
+ asprintf(&str, "%s/%08x/", slots, function_id) >= 0 &&
+ access(str, R_OK) == 0) {
+ hotplug_slot = function_id;
+ domain = 0;
+ } else
+ log_debug("No matching slot for function_id (%s).", attr);
+ break;
+ }
+ }
+
FOREACH_DIRENT_ALL(dent, dir, break) {
int i, r;
char str[PATH_MAX];