On Thu, Mar 28, 2024 at 10:22 AM Tejun Heo tj@kernel.org wrote:
Hello, Djalal.
On Wed, Mar 27, 2024 at 11:53:22PM +0100, Djalal Harouni wrote:
This patch series adds support to freeze the task cgroup hierarchy that is on a default cgroup v2 without going through kernfs interface.
For some cases we want to freeze the cgroup of a task based on some signals, doing so from bpf is better than user space which could be too late.
Planned users of this feature are: tetragon and systemd when freezing a cgroup hierarchy that could be a K8s pod, container, system service or a user session.
Patch 1: cgroup: add cgroup_freeze_no_kn() to freeze a cgroup from bpf Patch 2: bpf: add bpf_task_freeze_cgroup() to freeze the cgroup of a task Patch 3: selftests/bpf: add selftest for bpf_task_freeze_cgroup
It bothers me a bit that it's adding a dedicated interface for something which already has a defined userspace interface. Would it be better to have kfunc wrappers for kernel_read() and kernel_write()?
How would that look ? prog cannot and shouldn't open a file. The seq_file would be passed/pinned by user space?