Currently, mount_sysfs() only creates /sys/fs/cgroup if cg_ns_supported().
The comment explains that we need to "Create mountpoint for
cgroups. Otherwise we are not allowed since we remount /sys read-only.";
that is: that we need to do it now, rather than later. However, the
comment doesn't do anything to explain why we only need to do this if
cg_ns_supported(); shouldn't we _always_ need to do it?
The answer is that if !use_cgns, then this was already done by the outer
child, so mount_sysfs() only needs to do it if use_cgns. Now,
mount_sysfs() doesn't know whether use_cgns, but !cg_ns_supported() implies
!use_cgns, so we can optimize" the case where we _know_ !use_cgns, and deal
with a no-op mkdir_p() in the false-positive where cgns_supported() but
!use_cgns.
But is it really much of an optimization? We're potentially spending an
access(2) (cg_ns_supported() could be cached from a previous call) to
potentially save an lstat(2) and mkdir(2); and all of them are on virtual
fileystems, so they should all be pretty cheap.
So, simplify and drop the conditional. It's a dubious optimization that
requires more text to explain than it's worth.
Remove "arbitrary named hierarchies" from the list of things that
cg_kernel_controllers() might return, and clarify that "name="
pseudo-controllers are not included in the returned list.
/proc/cgroups does not contain "name=" pseudo-controllers, and
cg_kernel_controllers() makes no effort to enumerate them via a different
mechanism.
One of the things that tmpfs_patch_options does is take an (optional) UID,
and insert "uid=${UID},gid=${UID}" into the options string. So we need a
uid_t argument, and a way of telling if we should use it. Fortunately,
that is built in to the uid_t type by having UID_INVALID as a possible
value.
So this is really a feature that requires one argument. Yet, it is somehow
taking 4! That is absurd. Simplify it to only take one argument, and have
that trickle all the way up to mount_all()'s usage.
Now, in may of the uses, the argument becomes
uid_shift == 0 ? UID_INVALID : uid_shift
because it used to treat uid_shift=0 as invalid unless the patch_ids flag
was also set. This keeps the behavior the same. Note that in all cases
where it is invoked, if !use_userns (sometimes called !userns), then
uid_shift is 0; we don't have to add any checks for that.
That said, I'm pretty sure that "uid=0" and not setting "uid=" are the
same, but Christian Brauner seemed to not think so when implementing the
cgns support. https://github.com/systemd/systemd/pull/3589
One of the things that mkdir_userns{,_p}() does is take an (optional) UID,
and chown the directory to that. So we need a uid_t argument, and a way of
telling if we should use that uid_t argument. Fortunately, that is built
in to the uid_t type by having UID_INVALID as a possible value.
However, currently mkdir_userns() also takes a MountSettingsMask and checks
a couple of bits in it to decide if it should perform the chown.
Drop the mask argument, and instead have the caller pass UID_INVALID if it
shouldn't chown.
User units were in the middle, which is just confusing. Let's discuss
all system units first, and all user units second.
I'm using "System manager units" and "user manager units" instead of the more
obvious "system units" and "user units", because there are also units like
"user@.service".
When we open our own little namespace for running our tests in, let's
turn off mount propagation only one way, rather than both ways. This is
better as this means we don't pin host mounts unnecessarily long in our
namespace, even though the host already got rid of them. This is because
MS_SLAVE in contrast to MS_PRIVATE allows umount events to propagate
from the host into our environment.
The original manpage says "Implies BBBAccounting" many times but actually that accounting is not implied by the respective resource control in v239 with the unified cgroup hierarchy. This commit removes those false explanations.
Looking at a recent Bad Day, my log contains over 100 lines of
systemd[23895]: Failed to connect to API bus: Connection refused
It is due to "systemd --user" retrying to connect to an API bus.[*] I
would prefer to avoid spamming the logs. I don't think it is good for us
to retry so much like this.
systemd was mislead by something setting DBUS_SESSION_BUS_ADDRESS. My best
guess is an unfortunate series of events caused gdm to set this. gdm has
code to start a session dbus if there is not a bus available already (and
in this case it exports the environment variable). I believe it does not
normally do this when running under systemd, because "systemd --user" and
hence "dbus.service" would already have been started by pam_systemd.
I see two possibilities
1. Rip out the check for DBUS_SESSION_BUS_ADDRESS entirely.
2. Only check for DBUS_SESSION_BUS_ADDRESS on startup. Not in the
"recheck" logic.
The justification for 2), is that the recheck is called from unit_notify(),
this is used to check whether the service just started (or stopped) was
"dbus.service". This reason for rechecking does not apply if we think
the session bus was started outside our logic.
But I think we can justify 1). dbus-daemon ships a statically-enabled
/usr/lib/systemd/user/dbus.service, which would conflict with an attempt to
use an external dbus. Also "systemd --user" is started from user@.service;
if you try to start it manually so that it inherits an environment
variable, it will conflict if user@.service was started by pam_systemd
(or loginctl enable-linger).
This allows aliases to be used for the basic modules we load from pid1 before
udev is started. In #9501 the kernel renamed autofs4 to autofs, with "autofs4"
as alias, but we wouldn't load the module, because we didn't follow aliases.
The kernel change was reverted, but it's probably better to support aliases.
Micmute Key support of ThinkCentre M820z and M920z
There was a ThinkCentre M800z Micmute Key support entry.
But on new models M820z and M920z, the lines must change a bit,
the keyboard:name... must change to evdev:name.
Already tested on the M820z and M920z hardwares.
Per Poettering's comment in https://github.com/systemd/systemd/pull/9619,
We better combine M800z and M820/M920z entries and use the "evdev" prefix.
These custom macros make the expression go through a function, in order
to prevent ASSERT_SIDE_EFFECT false positives on our macros such as
assert_se() and assert_return() that cannot be disabled and will always
evaluate their expressions.
This technique has been described and recommended in:
https://community.synopsys.com/s/question/0D534000046Yuzb/suppressing-assertsideeffect-for-functions-that-allow-for-sideeffects
Tested by doing a local cov-build and uploading the resulting tarball to
scan.coverity.com, confirmed that the ASSERT_SIDE_EFFECT false positives
were gone.
This makes bus_slot_disconnect() unref the slot object from bus when
`unref == true` and it is floating, as the function removes the
reference from the relevant bus object.
This reverts 20d4ee2cbc, as it
introduces #9604.
Fixes#9604.
