Re: [PATCHv3 1/7] uprobe: Add support for session consumer

Oleg Nesterov
2024-09-12T16:36:08Z

On 09/09, Jiri Olsa wrote:
>
> handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs)
> {
> + struct return_consumer *ric = NULL;
> struct uprobe *uprobe = ri->uprobe;
> struct uprobe_consumer *uc;
> - int srcu_idx;
> + int srcu_idx, iter = 0;
>
> srcu_idx = srcu_read_lock(&uprobes_srcu);
> list_for_each_entry_srcu(uc, &uprobe->consumers, cons_node,
> srcu_read_lock_held(&uprobes_srcu)) {
> + /*
> + * If we don't find return consumer, it means uprobe consumer
> + * was added after we hit uprobe and return consumer did not
> + * get registered in which case we call the ret_handler only
> + * if it's not session consumer.
> + */
> + ric = return_consumer_find(ri, &iter, uc->id);
> + if (!ric && uc->session)
> + continue;
> if (uc->ret_handler)
> - uc->ret_handler(uc, ri->func, regs);
> + uc->ret_handler(uc, ri->func, regs, ric ? &ric->cookie : NULL);

So why do we need the new uc->session member and the uc->session above ?

If return_consumer_find() returns NULL, uc->ret_handler(..., NULL) can handle
this case itself?

Oleg.