p11-kit-proxy.so deadlocks if a child process calls C_Initialize() again after forking. Which is the behaviour that the PKCS#11 Users Guide recommends.
A patch was sent upstream: http://lists.freedesktop.org/archives/p11-glue/2015-June/date.html
Thanks Nikos. Patches merged upstream. David will do some testing ... then I'll do a point release.
p11-kit-0.23.1-2.fc22 has been submitted as an update for Fedora 22. https://admin.fedoraproject.org/updates/p11-kit-0.23.1-2.fc22
Package p11-kit-0.23.1-2.fc22: * should fix your issue, * was pushed to the Fedora 22 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=updates-testing p11-kit-0.23.1-2.fc22' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/FEDORA-2015-11023/p11-kit-0.23.1-2.fc22 then log in and leave karma (feedback).
p11-kit-0.23.1-2.fc22 has been pushed to the Fedora 22 stable repository. If problems still persist, please make note of it in this bug report.