Hello,
On Fri, Dec 22, 2023 at 11:31:01AM +0000, Yafang Shao wrote:
> Introducing a new kfunc: bpf_cpumask_set_from_pid. This function serves the
> purpose of retrieving the cpumask associated with a specific PID. Its
> utility is particularly evident within container environments. For
> instance, it allows for extracting the cpuset of a container using the
> init task within it.
>
> Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
...
> +__bpf_kfunc bool bpf_cpumask_set_from_pid(struct cpumask *cpumask, u32 pid)
> +{
> + struct task_struct *task;
> +
> + if (!cpumask)
> + return false;
> +
> + task = get_pid_task(find_vpid(pid), PIDTYPE_PID);
> + if (!task)
> + return false;
> +
> + cpumask_copy(cpumask, task->cpus_ptr);
> + put_task_struct(task);
> + return true;
> +}
This seems awfully specific. Why is this necessary? Shouldn't the BPF prog
get the task and bpf_cpumask_copy() its ->cpus_ptr instead?
Thanks.
--
tejun
