cgroup: remove support for NetClass= directive Support for net_cls.class_id through the NetClass= configuration directive has been added in v227 in preparation for a per-unit packet filter mechanism. However, it turns out the kernel people have decided to deprecate the net_cls and net_prio controllers in v2. Tejun provides a comprehensive justification for this in his commit, which has landed during the merge window for kernel v4.5: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=bd1060a1d671 As we're aiming for full support for the v2 cgroup hierarchy, we can no longer support this feature. Userspace tool such as nftables are moving over to setting rules that are specific to the full cgroup path of a task, which obsoletes these controllers anyway. This commit removes support for tweaking details in the net_cls controller, but keeps the NetClass= directive around for legacy compatibility reasons.

tree-wide: remove Emacs lines from all files This should be handled fine now by .dir-locals.el, so need to carry that stuff in every file.

tree-wide: check if errno is greater than zero (2) Compare errno with zero in a way that tells gcc that (if the condition is true) errno is positive.

tree-wide: check if errno is greater then zero gcc is confused by the common idiom of return errno ? -errno : -ESOMETHING and thinks a positive value may be returned. Replace this condition with errno > 0 to help gcc and avoid many spurious warnings. I filed a gcc rfe a long time ago, but it hard to say if it will ever be implemented [1]. Both conventions were used in the codebase, this change makes things more consistent. This is a follow up to bcb161b0230f. [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61846

tree-wide: use xsprintf() where applicable Also add a coccinelle receipt to help with such transitions.

tests: turn check if manager cannot be intialized into macro We need to check the same thing in multiple tests. Use a shared macro to make it easier to update the list of errnos. Change the errno code for "unitialized cgroup fs" for ENOMEDIUM. Exec format error looks like something more serious. This fixes test-execute invocation in mock.

basic: re-sort includes My previous patch to only include what we use accidentially placed the added inlcudes in non-sorted order.

basic: include only what we use This is a cleaned up result of running iwyu but without forward declarations on src/basic.

util-lib: split out allocation calls into alloc-util.[ch]

stat-util.h: move F_TYPE_EQUAL() macro definition to stat-util.h

util-lib: move /proc/cmdline parsing code to proc-cmdline.[ch]

util-lib: move string table stuff into its own string-table.[ch]

util-lib: move a number of fs operations into fs-util.[ch]

util-lib: introduce dirent-util.[ch] for directory entry calls Also, move a couple of more path-related functions to path-util.c.

util-lib: split string parsing related calls from util.[ch] into parse-util.[ch]

util-lib: split out user/group/uid/gid calls into user-util.[ch]

util-lib: split out fd-related operations into fd-util.[ch] There are more than enough to deserve their own .c file, hence move them over.

util-lib: split our string related calls from util.[ch] into its own file string-util.[ch] There are more than enough calls doing string manipulations to deserve its own files, hence do something about it. This patch also sorts the #include blocks of all files that needed to be updated, according to the sorting suggestions from CODING_STYLE. Since pretty much every file needs our string manipulation functions this effectively means that most files have sorted #include blocks now. Also touches a few unrelated include files.

util: split out extract_first_word() and related calls into extract-word.[ch] This is quite a lot of code these days, hence move it to its own source file.

cgroup: add support for net_cls controllers Add a new config directive called NetClass= to CGroup enabled units. Allowed values are positive numbers for fix assignments and "auto" for picking a free value automatically, for which we need to keep track of dynamically assigned net class IDs of units. Introduce a hash table for this, and also record the last ID that was given out, so the allocator can start its search for the next 'hole' from there. This could eventually be optimized with something like an irb. The class IDs up to 65536 are considered reserved and won't be assigned automatically by systemd. This barrier can be made a config directive in the future. Values set in unit files are stored in the CGroupContext of the unit and considered read-only. The actually assigned number (which may have been chosen dynamically) is stored in the unit itself and is guaranteed to remain stable as long as the unit is active. In the CGroup controller, set the configured CGroup net class to net_cls.classid. Multiple unit may share the same net class ID, and those which do are linked together.

core: refactor cpu shares/blockio weight cgroup logic Let's stop using the "unsigned long" type for weights/shares, and let's just use uint64_t for this, as that's what we expose on the bus. Unify parsers, and always validate the range for these fields. Correct the default blockio weight to 500, since that's what the kernel actually uses. When parsing the weight/shares settings from unit files accept the empty string as a way to reset the weight/shares value. When getting it via the bus, uniformly map (uint64_t) -1 to unset. Open up StartupCPUShares= and StartupBlockIOWeight= to transient units.

core: add support for the "pids" cgroup controller This adds support for the new "pids" cgroup controller of 4.3 kernels. It allows accounting the number of tasks in a cgroup and enforcing limits on it. This adds two new setting TasksAccounting= and TasksMax= to each unit, as well as a gloabl option DefaultTasksAccounting=. This also updated "cgtop" to optionally make use of the new kernel-provided accounting. systemctl has been updated to show the number of tasks for each service if it is available. This patch also adds correct support for undoing memory limits for units using a MemoryLimit=infinity syntax. We do the same for TasksMax= now and hence keep things in sync here.

cgroups: make sure the "devices" controller's enum is named the same way as the controller in the kernel Follow-up to 5bf8002a3a6723ce50331c024122078552fb600a.

cgroup-util: fix devices controller Commit efdb0237 accidentally changed the name of the "devices" cgroup controller to "device".

nspawn: enable all controllers we can for the "payload" subcgroup we create In the unified hierarchy delegating controller access is safe, hence make sure to enable all controllers for the "payload" subcgroup if we create it, so that the container will have all controllers enabled the nspawn service itself has.

cgroup: always read the supported controllers from the root cgroup of the local container Otherwise we might end up thinking that we support more controllers than actually enabled for the container we are running in.

cgroup: fix potential access of uninitialized variable

cgroup-util: make cg_pid_get_path() return -ENODATA when controller can't be found If the controller managed by systemd cannot found in /proc/$PID/cgroup, return ENODATA, the usual error for cases where the data being looked for does not exist, even if the process does.

cgroup: fix potential bad memory access

cgroup: make sure cg_is_empty_recursive() returns 1 for non-existing cgroups Previously, on the legacy hierarchy a non-existing cgroup was considered identical to an empty one, but the unified hierarchy the check for a non-existing one returned ENOENT.

cgroup: when comparing agent paths, use path_equal() After all a path is a path is a path and we should use path_equal() to comapre those.

cgroup: move controller to dirname translation into join_path_legacy() Let's simplify things a bit.

macro: introduce new PID_TO_PTR macros and make use of them This adds a new PID_TO_PTR() macro, plus PTR_TO_PID() and makes use of it wherever we maintain processes in a hash table. Previously we sometimes used LONG_TO_PTR() and other times ULONG_TO_PTR() for that, hence let's make this more explicit and clean up things.

cg_get_path: Removed unreachable statement controller cannot be NULL because if-statement in L509 has return Coverity #1322379

tree-wide: fix indentation

core: unified cgroup hierarchy support This patch set adds full support the new unified cgroup hierarchy logic of modern kernels. A new kernel command line option "systemd.unified_cgroup_hierarchy=1" is added. If specified the unified hierarchy is mounted to /sys/fs/cgroup instead of a tmpfs. No further hierarchies are mounted. The kernel command line option defaults to off. We can turn it on by default as soon as the kernel's APIs regarding this are stabilized (but even then downstream distros might want to turn this off, as this will break any tools that access cgroupfs directly). It is possibly to choose for each boot individually whether the unified or the legacy hierarchy is used. nspawn will by default provide the legacy hierarchy to containers if the host is using it, and the unified otherwise. However it is possible to run containers with the unified hierarchy on a legacy host and vice versa, by setting the $UNIFIED_CGROUP_HIERARCHY environment variable for nspawn to 1 or 0, respectively. The unified hierarchy provides reliable cgroup empty notifications for the first time, via inotify. To make use of this we maintain one manager-wide inotify fd, and each cgroup to it. This patch also removes cg_delete() which is unused now. On kernel 4.2 only the "memory" controller is compatible with the unified hierarchy, hence that's the only controller systemd exposes when booted in unified heirarchy mode. This introduces a new enum for enumerating supported controllers, plus a related enum for the mask bits mapping to it. The core is changed to make use of this everywhere. This moves PID 1 into a new "init.scope" implicit scope unit in the root slice. This is necessary since on the unified hierarchy cgroups may either contain subgroups or processes but not both. PID 1 hence has to move out of the root cgroup (strictly speaking the root cgroup is the only one where processes and subgroups are still allowed, but in order to support containers nicey, we move PID 1 into the new scope in all cases.) This new unit is also used on legacy hierarchy setups. It's actually pretty useful on all systems, as it can then be used to filter journal messages coming from PID 1, and so on. The root slice ("-.slice") is now implicitly created and started (and does not require a unit file on disk anymore), since that's where "init.scope" is located and the slice needs to be started before the scope can. To check whether we are in unified or legacy hierarchy mode we use statfs() on /sys/fs/cgroup. If the .f_type field reports tmpfs we are in legacy mode, if it reports cgroupfs we are in unified mode. This patch set carefuly makes sure that cgls and cgtop continue to work as desired. When invoking nspawn as a service it will implicitly create two subcgroups in the cgroup it is using, one to move the nspawn process into, the other to move the actual container processes into. This is done because of the requirement that cgroups may either contain processes or other subgroups.

cgroup: the root cgroup is always populated

cgroup: drop "ignore_self" argument from cg_is_empty() In all cases where the function (or cg_is_empty_recursive()) ignoring the calling process is actually wrong, as a process keeps a cgroup busy regardless if its the current one or another. Hence, let's simplify things and drop the "ignore_self" parameter.

cgroup: small cleanups and coding style fixes A number of simplications and adjustments to brings things closer to our coding style.

cgroup: don't allow hidden cgroups We really should care for all cgroups, and not allow hidden ones.

cgroup: never migrate kernel threads out of the root cgroup It won't work anyway.

tree-wide: convert some more mfree() candidates

fileio: consolidate write_string_file*() Merge write_string_file(), write_string_file_no_create() and write_string_file_atomic() into write_string_file() and provide a flags mask that allows combinations of atomic writing, newline appending and automatic file creation. Change all users accordingly.

cgroup-util: actually use the path callback We allow to specify a callback but then ignore the result. Looks like a trivial typo. From 7b3fd6313c4b07b6f822a9f979d0c22350a401d9#diff-f010fa21ba7b659b519c122743e55604

build-sys: split internal basic/ library from shared/ basic/ can be used by everything cannot use anything outside of basic/ libsystemd/ can use basic/ cannot use shared/ shared/ can use libsystemd/