Hello, 在 2023/10/20 08:03, Alexei Starovoitov 写道:
On Tue, Oct 17, 2023 at 11:18 PM Chuyi Zhou <zhouchuyi@xxxxxxxxxxxxx> wrote:+ +SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") +__failure __msg("css_task_iter is only allowed in bpf_lsm and bpf iter-s") +int BPF_PROG(iter_css_task_for_each) +{ + u64 cg_id = bpf_get_current_cgroup_id(); + struct cgroup *cgrp = bpf_cgroup_from_id(cg_id); + struct cgroup_subsys_state *css; + struct task_struct *task; + + if (cgrp == NULL) + return 0; + css = &cgrp->self; + + bpf_for_each(css_task, task, css, CSS_TASK_ITER_PROCS) { + + } + bpf_cgroup_release(cgrp); + return 0; +}I think we should relax allowlist in patch 2 further. Any sleepable is safe. Allowlist is needed to avoid dead locking on css_set_lock. Any lsm and any iter (even non-sleepable) and any sleepable seems to be safe. Then the above test would need s/fentry.s/fentry/ to stay relevant. I would also add: SEC("iter/cgroup") int cgroup_id_printer(struct bpf_iter__cgroup *ctx) { struct seq_file *seq = ctx->meta->seq; struct cgroup *cgrp = ctx->cgroup; /* epilogue */ if (cgrp == NULL) .. bpf_for_each(css_task, task, css, CSS_TASK_ITER_PROCS) { BPF_SEQ_PRINTF(); // something about task } To demonstrate how new kfunc iter can be combined with cgroup iter and it won't deadlock, though cgroup iter is not sleepable.
OK.
I've applied the current set. Pls send a follow up. Thanks
I would try to send a follow up patch next week. Thank.
