Created attachment 1036279 [details]
strace of ofws

Description of problem:

On starting ofws daemon I find that the process blocks accessing the USB subsystem.  The process is left in uninterruptable sleep.  Once in this state there are other side effects which include:

* lsusb fails (blocks, un-killable)

* long delays experienced on login or running su.


Version-Release number of selected component (if applicable):

owfs-server-3.0p0-2.fc22.x86_64


How reproducible:

every time.

Steps to Reproduce:

0. reboot, making sure owfs service is disabled.  Two DS9490R USB-to-1wire adapters plugged in.

1. start owfs from root shell with:

   /usr/bin/owfs -uall /run/owfs

or with:

   /usr/bin/owfs -u /run/owfs


Actual results:

owfs blocks.  /run/owfs file system does not get mounted.  strace reveals that owfs is blocked awaiting return of USB ioctl call.

Secondary effects are that now lsusb command fails and logins/su experience delay of about 25 seconds.

Same behaviour is shown if I only have a single one-wire adapter connected.

I have no other way to access the one-wire bus.


Expected results:

Expect owfs to lead to one-wire file system being accessible under /run/owfs.


Additional info:

Running x86_64 on Intel NUC hardware. SELinux is disabled.  

This is on a system upgraded from Fedora 20 on which owfs worked as expected.  Only change was upgrade to Fedora 22.

Strace output attached. Open file descriptors at time of strace as below:

# cd /proc/2040/fd
# ls -l
total 0
lrwx------ 1 root root 64 Jun  8 17:12 0 -> /dev/pts/0
lrwx------ 1 root root 64 Jun  8 17:12 1 -> /dev/pts/0
lrwx------ 1 root root 64 Jun  8 17:12 10 -> anon_inode:[timerfd]
lrwx------ 1 root root 64 Jun  8 17:12 11 -> /dev/bus/usb/001/003
lrwx------ 1 root root 64 Jun  8 17:12 2 -> /dev/pts/0
lrwx------ 1 root root 64 Jun  8 17:12 3 -> socket:[27672]
lr-x------ 1 root root 64 Jun  8 17:12 4 -> pipe:[27673]
l-wx------ 1 root root 64 Jun  8 17:12 5 -> pipe:[27673]
lr-x------ 1 root root 64 Jun  8 17:12 6 -> pipe:[27674]
l-wx------ 1 root root 64 Jun  8 17:12 7 -> pipe:[27674]
lr-x------ 1 root root 64 Jun  8 17:12 8 -> pipe:[27675]
l-wx------ 1 root root 64 Jun  8 17:12 9 -> pipe:[27675]


Output of ps at time of strace as below:

# ps auxw
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root      2040  0.0  0.1  48896  4000 pts/0    D+   17:12   0:00 /usr/bin/owfs -u /run/owfs


Output of lsusb prior to running strace,owfs as below:

# lsusb
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 007: ID 8087:07dc Intel Corp. 
Bus 001 Device 005: ID 046d:c534 Logitech, Inc. Unifying Receiver
Bus 001 Device 003: ID 04fa:2490 Dallas Semiconductor DS1490F 2-in-1 Fob, 1-Wire adapter
Bus 001 Device 006: ID 0403:8a28 Future Technology Devices International, Ltd Rainforest Automation ZigBee Controller
Bus 001 Device 004: ID 2001:1a02 D-Link Corp. DUB-E100 Fast Ethernet Adapter(rev.C1) [ASIX AX88772]
Bus 001 Device 002: ID 2109:2811 VIA Labs, Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub