Currently we are creating the worker process after creation of the pidfile.
This means that the responsibility of deleting the pidfile after process
termination rests with the worker process.
When we restart openvswitch using the startup scripts, we SIGTERM the main
process and once it is cleaned up, we start ovs-vswitchd again. This results
in a race condition. The new ovs-vswitchd will create a pidfile because it is
unlocked. But, if the old worker process exits after the start of new
ovs-vswitchd, it will simply delete the pidfile underneath the new ovs-vswitchd.
This will eventually result in multiple ovs-vswitchd daemons.
This patch gives the responsibility of deleting the pidfile to the main
process.
Bug #16669.
Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Replaced all instances of Nicira Networks(, Inc) to Nicira, Inc.
Feature #10593
Signed-off-by: Raju Subramanian <rsubramanian@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
Until now, it has been the responsibility of an individual daemon to call
die_if_already_running() at an appropriate time. A long time ago, this
had to happen *before* daemonizing, because once the process daemonized
itself there was no way to report failure to the process that originally
started the daemon. With the introduction of daemonize_start(), this is
now possible, but we haven't been taking advantage of it.
Therefore, this commit integrates the die_if_already_running() call into
daemonize_start() and deletes the calls to it from individual daemons.
Other modules that accept options use this style and I don't see a reason
for the daemon code to be different. The style used by the daemon code
until now runs the risk of ending up with conflicting values accidentally,
which would be confusing.
There are conflicting pressures in startup of a daemon process:
* The parent process should exit with an error code if the daemon
cannot start up successfully.
* Some startup actions must be performed in the child process, not in
the parent. The most obvious of these are file locking, since
child processes do not inherit locks, and anything that requires
knowing the child process's PID (e.g. unixctl sockets).
Until now, this conflict has usually been handled by giving up part of the
first property, i.e. in some cases the parent process would exit
successfully and the child immediately afterward exit with a failure code.
This commit introduces a better approach, by allowing daemons to perform
startup work in the child and only then signal the parent that they have
successfully started. If the child instead exits without signaling
success, the parent passes this exit code along to its own parent.
This commit also modifies the daemons that can usefully take advantage of
this new feature to do so.
Before this commit, "ovsdb-server --detach" would detach after it opened
the database file, which meant that the child process did not hold the
file lock on the database file (because a forked child process does not
inherit its parents' locks). This commit fixes the problem by making
ovsdb-server open the database only after it has detached. This fix, in
turn, required that daemonize() not chdir to /, because this would break
databases whose names are given relative to the current directory, and so
this commit also changes ovsdb-server to do so later.
The daemon library provides a few short options, but these then take
away their availability from programs that wish to use the library.
Since the daemon options are generally going to be called from a script
(which doesn't care how much typing is involved), we'll only provide
long options.
By default, Open vSwitch daemons change their working directories to the
root directory. This commit provides a --no-chdir option to prevent this
behavior.
