There's been a report on the upstream list [1] describing we
access /sys/devices/system/cpu/present directly on the host from
within our test suite. This may end up in unpredictable results
as no all linux systems are required to have that file. Mock
access to the file.
libvirt.git/tests $ ../run strace vircgrouptest
...
access("/sys/devices/system/cpu/present", F_OK) = 0
...
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Instead of fakesysfsdir, which is very generic, use fakesysfspcidir and
fakesysfscgroupdir. This makes it explicit what part of the fake sysfs
filesystem they're referring to, and also leaves open the possibility of
handling files in two unrelated parts of the fake sysfs filesystem.
No functional changes.
We might need to mock files living outside SYSFS_PREFIX later on,
so it's better to treat the temporary directory we are passed via
the environment as the root of the fake filesystem and create
SYSFS_PREFIX inside it.
The environment variable name will be changed to reflect the new use
we're making of it in a later commit.
Per-cpu stats are only shown for present CPUs in the cgroups,
but we were only parsing the largest CPU number from
/sys/devices/system/cpu/present and looking for stats even for
non-present CPUs.
This resulted in:
internal error: cpuacct parse error
Most of our code base uses space after comma but not before;
fix the remaining uses before adding a syntax check.
* tests/sysinfotest.c: Consistently use commas.
* tests/viratomictest.c: Likewise.
* tests/vircgroupmock.c: Likewise.
* tools/virsh-domain.c: Likewise.
* tools/virsh-volume.c: Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
Currently, if access(path, mode) is invoked, we check if @path has this
special prefix SYSFS_PREFIX. If it does, we modify the path a bit and
call realaccess. If it doesn't we act just like a wrapper and call
realaccess directly. However, we are mocking fopen() as well. And as one
can clearly see there, fopen("/proc/cgroups") will succeed. Hence, we
have an error in our mocked access(): We need to check whether @path is
not equal to /proc/cgroups as it may not exists on real system we're
running however we definitely know how to fopen() it.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Debian systems may run the 'systemd-logind' daemon, which causes the
/sys/fs/cgroup/systemd mount to be setup, but no other cgroup
controllers are created. While the LXC driver considers cgroups to
be mandatory, the QEMU driver is supposed to accept them as optional.
We detect whether they are present by looking in /proc/mounts for
any mounts of type 'cgroups', but this is not sufficient. We need to
skip any named mounts (as seen by a name=XXX string in the mount
options), so that we only detect actual resource controllers.
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=721979
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Some users in Ubuntu/Debian seem to have a setup where all the
cgroup controllers are mounted on /sys/fs/cgroup rather than
any /sys/fs/cgroup/<controller> name. In the loop which detects
which controllers are present for a mount point we were modifying
'mnt_dir' field in the 'struct mntent' var, but not always restoring
the original value. This caused detection to break in the all-in-one
mount setup.
Fix that logic bug and add test case coverage for this mount
setup.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Clang does not like it when you pass a static variable to an
inline function
vircgroupmock.c:462:22: error: static variable 'fakesysfsdir' is
used in an inline function with external linkage [-Werror,-Wstatic-in-inline]
Just make the var non-static to avoid this
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
If a user cgroup name begins with "cgroup.", "_" or with any of
the controllers from /proc/cgroups followed by a dot, then they
need to be prefixed with a single underscore. eg if there is
an object "cpu.service", then this would end up as "_cpu.service"
in the cgroup filesystem tree, however, "waldo.service" would
stay "waldo.service", at least as long as nobody comes up with
a cgroup controller called "waldo".
Since we require a '.XXXX' suffix on all partitions, there is
no scope for clashing with the kernel 'tasks' and 'release_agent'
files.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
If a cgroup controller is co-mounted with another, eg
/sys/fs/cgroup/cpu,cpuacct
Then it is a requirement that there exist symlinks at
/sys/fs/cgroup/cpu
/sys/fs/cgroup/cpuacct
pointing to the real mount point. Add support to virCgroupPtr
to detect and track these symlinks
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Some aspects of the cgroups setup / detection code are quite subtle
and easy to break. It would greatly benefit from unit testing, but
this is difficult because the test suite won't have privileges to
play around with cgroups. The solution is to use monkey patching
via LD_PRELOAD to override the fopen, open, mkdir, access functions
to redirect access of cgroups files to some magic stubs in the
test suite.
Using this we provide custom content for the /proc/cgroup and
/proc/self/mounts files which report a fixed cgroup setup. We
then override open/mkdir/access so that access to the cgroups
filesystem gets redirected into files in a temporary directory
tree in the test suite build dir.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
