Add note for change of behaviour in systemd-notify, where parent pid trick
is only used when --no-block is passed, and with enough privileges ofcourse.
Also, fix a small error in systemd(1).
This adds the sd_notify_barrier function, to allow users to synchronize against
the reception of sd_notify(3) status messages. It acts as a synchronization
point, and a successful return gurantees that all previous messages have been
consumed by the manager. This can be used to eliminate race conditions where
the sending process exits too early for systemd to associate its PID to a
cgroup and attribute the status message to a unit correctly.
systemd-notify now uses this function for proper notification delivery and be
useful for NotifyAccess=all units again in user mode, or in cases where it
doesn't have a control process as parent.
Fixes: #2739
A service can specify FDSTORE=1 FDPOLL=0 to request that PID1 does not
poll the fd to remove them on error. If set, fds will only be removed on
FDSTOREREMOVE=1 or when the service is done.
Fixes: #12086
With cgroup v2 the cgroup freezer is implemented as a cgroup
attribute called cgroup.freeze. cgroup can be frozen by writing "1"
to the file and kernel will send us a notification through
"cgroup.events" after the operation is finished and processes in the
cgroup entered quiescent state, i.e. they are not scheduled to
run. Writing "0" to the attribute file does the inverse and process
execution is resumed.
This commit exposes above low-level functionality through systemd's DBus
API. Each unit type must provide specialized implementation for these
methods, otherwise, we return an error. So far only service, scope, and
slice unit types provide the support. It is possible to check if a
given unit has the support using CanFreeze() DBus property.
Note that DBus API has a synchronous behavior and we dispatch the reply
to freeze/thaw requests only after the kernel has notified us that
requested operation was completed.
It turns out that our man page didn't describe the handling of single-label
names almost at all. This probably adds to the confusion regarding the subject.
So let's first describe what our current implementation is doing.
Quoting https://www.iab.org/documents/correspondence-reports-documents/2013-2/iab-statement-dotless-domains-considered-harmful/:
> Applications and platforms that apply a suffix search list to a single-label
> name are in conformance with IETF standards track RFCs. Furthermore,
> applications and platforms that do not query DNS for a TLD are in conformance
> with IETF standards track recommendations
Current behaviour is in line with that recommendation.
For #13763.
Anyone previously using the UseRoutes=false parameter expected their
dhcp4-provided gateway route to be ignored, as well. However, with
the introduction of the UseGateway= parameter, this is no longer true.
In order to keep backwards compatibility, this sets the UseGateway=
default value to whatever UseRoutes= has been set to.
