On 06/28, Ravi Bangoria wrote:
>
> @@ -294,6 +462,15 @@ int uprobe_write_opcode(struct uprobe *uprobe, struct mm_struct *mm,
> if (ret <= 0)
> goto put_old;
>
> + /* Update the ref_ctr if we are going to replace instruction. */
> + if (!ref_ctr_updated) {
> + ret = update_ref_ctr(uprobe, mm, is_register);
> + if (ret)
> + goto put_old;
> +
> + ref_ctr_updated = 1;
> + }
Why can't this code live in install_breakpoint() and remove_breakpoint() ?
this way we do not need to export "struct uprobe" and change set_swbp/set_orig_insn,
and the logic will be more simple.
And let me ask again... May be you have already explained this, but I can't
find the previous discussion.
So why do we need a counter but not a boolean? IIRC, because the counter can
be shared, in particular 2 different uprobes can have the same >ref_ctr_offset,
right?
But who else can use this counter and how? Say, can userspace update it too?
If yes, why this can't race with __update_ref_ctr() ?
And btw, why does __update_ref_ctr() use FOLL_FORCE? This vma should be writeable
or valid_ref_ctr_vma() should nack it?
And shouldn't valid_ref_ctr_vma() check VM_SHARED? IIUC we do not want to write
to this file?
Oleg.
