From 9a9c7dc2cbbe3c26cfbbcb02475d95ff3afe507e Mon Sep 17 00:00:00 2001 From: Maxim Mikityanskiy Date: Sat, 22 Aug 2015 11:33:32 +0300 Subject: [PATCH] sd-device: fix enumeration of devices without subsystem Prior to commit c32eb440bab953a0169cd207dfef5cad16dfb340, libudev's function udev_enumerate_scan_devices() had behaved differently. If parent match was added with udev_enumerate_add_match_parent(), udev_enumerate_scan_devices() did not return error if some child devices had no subsystem symlink in sysfs. An example of such devices is USB endpoints /sys/bus/usb/devices/*/ep_*. If there was a parent match against USB device, old implementation of udev_enumerate_scan_devices() did not treat ep_* device directories without subsystem symlink as error and just ignored them, but new implementation returns -ENOENT (also ignoring these devices) though correctly enumerates all other matching devices. To compare, you could look at 96df036fe3d25525a44f5efdb2fc8560e82e6cfd, in src/libudev/libudev-enumerate.c, function parent_add_child(): if (!match_subsystem(enumerate, udev_device_get_subsystem(dev))) goto nomatch; udev_device_get_subsystem() was returning NULL, match_subsystem() was returning false, and USB endpoint device was ignored. New parent_add_child() from src/libsystemd/sd-device/device-enumerator.c checks return value of sd_device_get_subsystem() and fails if subsystem was not found. Absence of subsystem symlink should not be really treated as error because all enumerations of children of USB devices will fail with -ENOENT. This new behavior also breaks system-config-printer. So restore old behavior and treat absence of subsystem symlink as no match. --- src/libsystemd/sd-device/device-enumerator.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/src/libsystemd/sd-device/device-enumerator.c b/src/libsystemd/sd-device/device-enumerator.c index 7fd77e94800..5eb37e16cbc 100644 --- a/src/libsystemd/sd-device/device-enumerator.c +++ b/src/libsystemd/sd-device/device-enumerator.c @@ -719,6 +719,8 @@ static int parent_add_child(sd_device_enumerator *enumerator, const char *path) return r; r = sd_device_get_subsystem(device, &subsystem); + if (r == -ENOENT) + return 0; if (r < 0) return r;