diff options
| -rw-r--r-- | man/systemd.service.xml | 25 |
1 files changed, 18 insertions, 7 deletions
diff --git a/man/systemd.service.xml b/man/systemd.service.xml index 735c98d1d6..123f1db30d 100644 --- a/man/systemd.service.xml +++ b/man/systemd.service.xml @@ -1064,14 +1064,25 @@ <varlistentry> <term><varname>NonBlocking=</varname></term> - <listitem><para>Set the <constant>O_NONBLOCK</constant> flag for all file descriptors passed via socket-based - activation. If true, all file descriptors >= 3 (i.e. all except stdin, stdout, stderr), excluding those passed - in via the file descriptor storage logic (see <varname>FileDescriptorStoreMax=</varname> for details), will - have the <constant>O_NONBLOCK</constant> flag set and hence are in non-blocking mode. This option is only + <listitem><para>Set the <constant>O_NONBLOCK</constant> flag for all file descriptors passed via + socket-based activation. If true, all file descriptors >= 3 (i.e. all except stdin, stdout, stderr), + excluding those passed in via the file descriptor storage logic (see + <varname>FileDescriptorStoreMax=</varname> for details), will have the + <constant>O_NONBLOCK</constant> flag set and hence are in non-blocking mode. This option is only useful in conjunction with a socket unit, as described in - <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry> and has no - effect on file descriptors which were previously saved in the file-descriptor store for example. Defaults to - false.</para></listitem> + <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry> + and has no effect on file descriptors which were previously saved in the file-descriptor store for + example. Defaults to false.</para> + + <para>Note that if the same socket unit is configured to be passed to multiple service units (via the + <varname>Sockets=</varname> setting, see below), and these services have different + <varname>NonBlocking=</varname> configurations, the precise state of <constant>O_NONBLOCK</constant> + depends on the order in which these services are invoked, and will possibly change after service code + already took possession of the socket file descriptor, simply because the + <constant>O_NONBLOCK</constant> state of a socket is shared by all file descriptors referencing + it. Hence it is essential that all services sharing the same socket use the same + <varname>NonBlocking=</varname> configuration, and do not change the flag in service code + either.</para></listitem> </varlistentry> <varlistentry> |