*From:* Patrick Hemmer <linux@xxxxxxxxxxxxxxx> *Sent:* 2014-08-15 19:46:21 EDT *To:* linux-hotplug@xxxxxxxxxxxxxxx *Subject:* device symlinks being removed > It seems I have some sort of race condition when using udev rules to set > up some device symlinks, but I'm not sure why. > I'm building EC2 boxes, and immediately after they boot, they add some > udev rules to create symlinks, and then call `udevadm trigger` to > process the rules. The problem is that during this procedure, sometimes > some of the links are missing. The udev debug log indicates the links > were created, and then subsequently removed. > > The complete system log can be viewed at http://dpaste.com/1BN5FKA > However I've grabbed what look like the interesting lines, and have > included them at the bottom. Notice the ones such as > > creating symlink '/dev/disk/ec2/vol-05b50706' to '../../xvda' > > and > > update old name, '/dev/disk/ec2/vol-05b50706' no longer belonging to > '/devices/vbd-2048/block/xvda' > no reference left, remove '/dev/disk/ec2/vol-05b50706' > > > My udev rule looks like this: > > SUBSYSTEM=="block", SUBSYSTEMS=="xen", ATTR{capability}=="*", > ACTION=="add", PROGRAM="/ec2disks -A %k", SYMLINK+="%c" > > My current process is: > > # create the file > /bin/udevadm control --reload > /bin/udevadm settle > /bin/udevadm trigger --subsystem-match=block --action=add > > > The system is using udev 215 > The only rule in /etc/udev/rules.d is my rule. All others should be the > standard rules. The distro is CoreOS. > > Log: > > > Aug 15 23:13:49 i-863204d8 systemd-udevd[629]: PROGRAM '/ec2disks -A > xvda' /etc/udev/rules.d/10-ec2disks.rules:1 > Aug 15 23:13:49 i-863204d8 systemd-udevd[630]: starting '/ec2disks > -A xvda' > Aug 15 23:13:49 i-863204d8 systemd-udevd[629]: '/ec2disks -A > xvda'(out) 'disk/ec2/ami disk/ec2/root disk/ec2/vol-05b50706' > Aug 15 23:13:49 i-863204d8 systemd-udevd[629]: '/ec2disks -A xvda' > [630] exit with return code 0 > Aug 15 23:13:49 i-863204d8 systemd-udevd[629]: LINK 'disk/ec2/ami' > /etc/udev/rules.d/10-ec2disks.rules:1 > Aug 15 23:13:49 i-863204d8 systemd-udevd[629]: LINK 'disk/ec2/root' > /etc/udev/rules.d/10-ec2disks.rules:1 > Aug 15 23:13:49 i-863204d8 systemd-udevd[629]: LINK > 'disk/ec2/vol-05b50706' /etc/udev/rules.d/10-ec2disks.rules:1 > Aug 15 23:13:49 i-863204d8 systemd-udevd[629]: IMPORT 'cdrom_id > --lock-media /dev/xvda' /usr/lib64/udev/rules.d/60-cdrom_id.rules:16 > Aug 15 23:13:49 i-863204d8 systemd-udevd[642]: starting 'cdrom_id > --lock-media /dev/xvda' > Aug 15 23:13:52 i-863204d8 systemd-udevd[629]: 'cdrom_id > --lock-media /dev/xvda'(err) 'unable to open '/dev/xvda'' > Aug 15 23:13:52 i-863204d8 systemd-udevd[629]: 'cdrom_id > --lock-media /dev/xvda' [642] exit with return code 1 > Aug 15 23:13:52 i-863204d8 systemd-udevd[629]: probe /dev/xvda raid > offset=0 > Aug 15 23:13:52 i-863204d8 systemd-udevd[629]: handling device node > '/dev/xvda', devnum=b202:0, mode=0660, uid=0, gid=6 > Aug 15 23:13:52 i-863204d8 systemd-udevd[629]: preserve permissions > /dev/xvda, 060660, uid=0, gid=6 > Aug 15 23:13:52 i-863204d8 systemd-udevd[629]: preserve already > existing symlink '/dev/block/202:0' to '../xvda' > Aug 15 23:13:52 i-863204d8 systemd-udevd[629]: creating link > '/dev/disk/ec2/ami' to '/dev/xvda' > Aug 15 23:13:52 i-863204d8 systemd-udevd[629]: creating symlink > '/dev/disk/ec2/ami' to '../../xvda' > Aug 15 23:13:52 i-863204d8 systemd-udevd[629]: creating link > '/dev/disk/ec2/root' to '/dev/xvda' > Aug 15 23:13:52 i-863204d8 systemd-udevd[629]: creating symlink > '/dev/disk/ec2/root' to '../../xvda' > Aug 15 23:13:52 i-863204d8 systemd-udevd[629]: creating link > '/dev/disk/ec2/vol-05b50706' to '/dev/xvda' > Aug 15 23:13:52 i-863204d8 systemd-udevd[629]: creating symlink > '/dev/disk/ec2/vol-05b50706' to '../../xvda' > Aug 15 23:13:52 i-863204d8 systemd-udevd[629]: created db file > '/run/udev/data/b202:0' for '/devices/vbd-2048/block/xvda' > Aug 15 23:13:52 i-863204d8 systemd-udevd[629]: adding watch on > '/dev/xvda' > Aug 15 23:13:52 i-863204d8 systemd-udevd[629]: created db file > '/run/udev/data/b202:0' for '/devices/vbd-2048/block/xvda' > Aug 15 23:14:31 i-863204d8 systemd-udevd[410]: Check if link > configuration needs reloading. > Aug 15 23:14:31 i-863204d8 systemd-udevd[410]: device 0x7f29dc30fc90 > has devpath '/devices/vbd-2048/block/xvda' > Aug 15 23:14:31 i-863204d8 systemd-udevd[410]: inotify event: 8 for > /dev/xvda > Aug 15 23:14:31 i-863204d8 systemd-udevd[410]: device 0x7f29dc31f350 > has devpath '/devices/vbd-2048/block/xvda' > Aug 15 23:14:31 i-863204d8 systemd-udevd[410]: device /dev/xvda > closed, synthesising 'change' > Aug 15 23:14:31 i-863204d8 systemd-udevd[731]: IMPORT 'cdrom_id > --lock-media /dev/xvda' /usr/lib64/udev/rules.d/60-cdrom_id.rules:16 > Aug 15 23:14:31 i-863204d8 systemd-udevd[732]: starting 'cdrom_id > --lock-media /dev/xvda' > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: 'cdrom_id > --lock-media /dev/xvda'(err) 'unable to open '/dev/xvda'' > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: 'cdrom_id > --lock-media /dev/xvda' [732] exit with return code 1 > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: IMPORT builtin > 'path_id' /usr/lib64/udev/rules.d/60-persistent-storage.rules:55 > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: device 0x7f29dc308070 > has devpath '/devices/vbd-2048' > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: IMPORT builtin > 'path_id' returned non-zero > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: IMPORT builtin > 'blkid' /usr/lib64/udev/rules.d/60-persistent-storage.rules:70 > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: probe /dev/xvda raid > offset=0 > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: no db file to read > /run/udev/data/+xen:vbd-2048: No such file or directory > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: update old name, > '/dev/disk/ec2/ami' no longer belonging to '/devices/vbd-2048/block/xvda' > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: no reference left, > remove '/dev/disk/ec2/ami' > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: update old name, > '/dev/disk/ec2/root' no longer belonging to '/devices/vbd-2048/block/xvda' > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: no reference left, > remove '/dev/disk/ec2/root' > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: update old name, > '/dev/disk/ec2/vol-05b50706' no longer belonging to > '/devices/vbd-2048/block/xvda' > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: no reference left, > remove '/dev/disk/ec2/vol-05b50706' > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: handling device node > '/dev/xvda', devnum=b202:0, mode=0600, uid=0, gid=0 > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: preserve already > existing symlink '/dev/block/202:0' to '../xvda' > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: created db file > '/run/udev/data/b202:0' for '/devices/vbd-2048/block/xvda' > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: adding watch on > '/dev/xvda' > Aug 15 23:14:34 i-863204d8 systemd-udevd[731]: created db file > '/run/udev/data/b202:0' for '/devices/vbd-2048/block/xvda' > > > > If someone can explain to me why the links are getting removed, I would > appreciate it. > > Thanks > > > -Patrick Finally figured out it. For some reason, another event was sometimes being triggered on the device. My udev rule was matching only 'add' events, and this other event was apparently something else. So my rule wouldn't match, and the device would lose the symlinks. Just removed the ACTION=="add" from the udev rule and all appears well. -Patrick -- To unsubscribe from this list: send the line "unsubscribe linux-hotplug" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
