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Description of problem:
If I listen on sock file which is the same for mariadb, starting of mariadb service hangs.

Version-Release number of selected component (if applicable):
mariadb-server-5.5.35-3.el7.x86_64

How reproducible:
always

Steps to Reproduce:
# systemctl stop mariadb
# ls /var/lib/mysql/mysql.sock
ls: cannot access /var/lib/mysql/mysql.sock: No such file or directory
# nc -k -l -U /var/lib/mysql/mysql.sock &
# chown mysql:mysql /var/lib/mysql/mysql.sock
# restorecon -v /var/lib/mysql/mysql.sock
restorecon reset /var/lib/mysql/mysql.sock context unconfined_u:object_r:mysqld_db_t:s0->unconfined_u:object_r:mysqld_var_run_t:s0
# systemctl start mariadb
.. it hangs here ..

This issue is caused by mysqladmin pinging the socket file and this tool expects the socket responds in a specific way, which doesn't happen (nc doesn't respond) and the mysqladmin tool waits for too long time by default. This time may either be shortened by using --connect-timeout=10 for example (shortens the hang to 10s) or better to use a check if socket is used before actually starting the daemon process, similar to what Fedora does:

http://pkgs.fedoraproject.org/cgit/mariadb.git/tree/mysql-check-socket.sh?id=c9d7d6f31d5f8ad7979201b65c03cb7fec4fd157

What is important, this shouldn't be a real issue, since if another mysql daemon is using the socket, the daemon's respond is sane and mysqladmin doesn't hang.