On 02/28, Anton Arapov wrote:
>
> +static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs)
> +{
> + struct return_uprobe_i *ri;
> + struct uprobe_task *utask;
> + struct xol_area *area;
> + unsigned long rp_trampoline_vaddr = 0;
> + uprobe_opcode_t insn = UPROBE_SWBP_INSN;
> +
> + area = get_xol_area();
> + if (area)
> + rp_trampoline_vaddr = area->rp_trampoline_vaddr;
> + if (!rp_trampoline_vaddr) {
> + rp_trampoline_vaddr = xol_get_insn_slot(&insn);
> + if (!rp_trampoline_vaddr)
> + return;
> + }
> + area->rp_trampoline_vaddr = rp_trampoline_vaddr;
This is called under down_read(), so 2 threads can race with each other
and use the different rp_trampoline_vaddr's if ->rp_trampoline_vaddr was
NULL.
And again, I think ->rp_trampoline_vaddr is simply unneeded, see my
reply to 3/6.
> static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs)
> {
> + int rc = 0;
> struct uprobe_consumer *uc;
> int remove = UPROBE_HANDLER_REMOVE;
>
> down_read(&uprobe->register_rwsem);
> for (uc = uprobe->consumers; uc; uc = uc->next) {
> - int rc = uc->handler(uc, regs);
> + if (uc->handler)
> + rc = uc->handler(uc, regs);
> +
> + if (uc->rp_handler)
> + prepare_uretprobe(uprobe, regs); /* put bp at return */
Hmm. I didn't read this series yet. But at first glance I am not
sure prepare_uretprobe() should be called every time we see
->rp_handler != NULL, there could be multiple consumers...
Oleg.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
