Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> writes:
Hi,
Sorry for the delay on this.
> On Wed, Jul 24, 2024 at 4:40 AM Puranjay Mohan <puranjay@xxxxxxxxxx> wrote:
>>
>> Implement bpf_send_signal_pid and bpf_send_signal_tgid helpers which are
>> similar to bpf_send_signal_thread and bpf_send_signal helpers
>> respectively but can be used to send signals to other threads and
>> processes.
>
> Thanks for working on this!
> But it needs more homework.
>
>> #define ___BPF_FUNC_MAPPER(FN, ctx...) \
>> FN(unspec, 0, ##ctx) \
>> @@ -6006,6 +6041,8 @@ union bpf_attr {
>> FN(user_ringbuf_drain, 209, ##ctx) \
>> FN(cgrp_storage_get, 210, ##ctx) \
>> FN(cgrp_storage_delete, 211, ##ctx) \
>> + FN(send_signal_pid, 212, ##ctx) \
>> + FN(send_signal_tgid, 213, ##ctx) \
>
> We stopped adding helpers long ago.
> They need to be kfuncs.
>
>> /* */
>>
>> /* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't
>> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
>> index cd098846e251..f1e58122600d 100644
>> --- a/kernel/trace/bpf_trace.c
>> +++ b/kernel/trace/bpf_trace.c
>> @@ -839,21 +839,30 @@ static void do_bpf_send_signal(struct irq_work *entry)
>> put_task_struct(work->task);
>> }
>>
>> -static int bpf_send_signal_common(u32 sig, enum pid_type type)
>> +static int bpf_send_signal_common(u32 sig, enum pid_type type, u32 pid)
>> {
>> struct send_signal_irq_work *work = NULL;
>> + struct task_struct *tsk;
>> +
>> + if (pid) {
>> + tsk = find_task_by_vpid(pid);
>
> by vpid ?
>
> tracing bpf prog will have "random" current and "random" pidns.
>
> Should it be find_get_task vs find_task too ?
>
> Should kfunc take 'task' parameter instead
> received from bpf_task_from_pid() ?
>
> two kfuncs for pid/tgid is overkill. Combine into one?
So, I will add a single kfunc that can do both pid and tgid and it will
take the 'task' parameter received from the call to bpf_task_from_pid()
and a 'bool' to select pid/tgid.
>
>> + if (!tsk)
>> + return -ESRCH;
>> + } else {
>> + tsk = current;
>> + }
Thanks,
Puranjay
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