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udev: derive path ID for PNP devices from ACPI firmware node

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PNP devices may represent ACPI-enumerated hardware but do not have a
parent type supported by path_id. Consequently, importing path_id fails
even when the PNP device exposes a stable ACPI firmware_node. This also
prevents later assignments in rules such as the systemd-backlight
activation rule from taking effect.

Resolve the PNP device's firmware_node and use its ACPI sysname for the
path component. This gives PNP-backed devices the same stable identity
as their firmware representation.

Add a regression test using an RTC device below a PNP parent with an
ACPI firmware node.
This commit is contained in:
Andre Eikmeyer
2026-08-02 15:48:41 +02:00
committed by Yu Watanabe
parent b6fba48f0f
commit 6044c31038
3 changed files with 40 additions and 0 deletions
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28
src/udev/udev-builtin-path_id.c
View File

@@ -677,6 +677,30 @@ static void add_id_tag(UdevEvent *event, const char *path) {
(void) udev_builtin_add_property(event, "ID_PATH_TAG", tag);
}
static int handle_pnp(sd_device *parent, char **path) {
_cleanup_(sd_device_unrefp) sd_device *firmware_node = NULL;
const char *sysname;
int r;
assert(parent);
assert(path);
r = sd_device_new_child(&firmware_node, parent, "firmware_node");
if (r < 0)
return r;
if (device_in_subsystem(firmware_node, "acpi") <= 0)
return -ENODEV;
r = sd_device_get_sysname(firmware_node, &sysname);
if (r < 0)
return r;
path_prepend(path, "acpi-%s", sysname);
return 0;
}
static int builtin_path_id(UdevEvent *event, int argc, char *argv[]) {
sd_device *dev = ASSERT_PTR(ASSERT_PTR(event)->dev);
_cleanup_(sd_device_unrefp) sd_device *dev_other_branch = NULL;
@@ -749,6 +773,10 @@ static int builtin_path_id(UdevEvent *event, int argc, char *argv[]) {
path_prepend(&compat_path, "acpi-%s", sysname);
parent = skip_subsystem(parent, "acpi");
supported_parent = true;
} else if (device_in_subsystem(parent, "pnp") > 0) {
if (handle_pnp(parent, &path) >= 0)
supported_parent = true;
parent = skip_subsystem(parent, "pnp");
} else if (device_in_subsystem(parent, "xen") > 0) {
path_prepend(&path, "xen-%s", sysname);
if (compat_path)

1
test/sys-script.py
View File

@@ -10584,6 +10584,7 @@ f('sys/devices/pnp0/00:07/rtc/rtc0/name', 0o644, b'rtc_cmos\n')
f('sys/devices/pnp0/00:07/rtc/rtc0/time', 0o644, b'02:30:51\n')
f('sys/devices/pnp0/00:07/rtc/rtc0/uevent', 0o644, b'''MAJOR=253
MINOR=0
DEVNAME=rtc0
''')
d('sys/devices/pnp0/00:07/rtc/rtc0/power', 0o755)
f('sys/devices/pnp0/00:07/rtc/rtc0/power/wakeup', 0o644, b'\n')

11
test/test-udev.py
View File

@@ -2071,6 +2071,17 @@ SUBSYSTEMS=="scsi", PROGRAM=="/bin/bash -c \"printf %%s 'foo1 foo2' | grep 'foo1
KERNEL=="sda", ENV{ID_PATH}=="?*", SYMLINK+="disk/by-path/$env{ID_PATH}"
''',
),
Rules.new(
'builtin path_id for PNP device with ACPI firmware node',
Device(
'/devices/pnp0/00:07/rtc/rtc0',
exp_links=['rtc/by-path/acpi-PNP0B00:00'],
),
rules=r'''
KERNEL=="rtc0", IMPORT{builtin}="path_id"
KERNEL=="rtc0", ENV{ID_PATH}=="?*", SYMLINK+="rtc/by-path/$env{ID_PATH}"
''',
),
Rules.new(
'add and match tag',
Device(