Re: [PATCH v4 3.0-rc2-tip 4/22] 4: Uprobes: register/unregister probes.

Srikar Dronamraju
2011-06-16T05:48:25Z

* Peter Zijlstra <peterz@infradead.org> [2011-06-10 01:03:24]:

> On Tue, 2011-06-07 at 18:29 +0530, Srikar Dronamraju wrote:
> > + vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, 0) {
> > + loff_t vaddr;
> > + struct task_struct *tsk;
> > +
> > + if (!atomic_inc_not_zero(&vma->vm_mm->mm_users))
> > + continue;
> > +
> > + mm = vma->vm_mm;
> > + if (!valid_vma(vma)) {
> > + mmput(mm);
> > + continue;
> > + }
> > +
> > + vaddr = vma->vm_start + offset;
> > + vaddr -= vma->vm_pgoff << PAGE_SHIFT;
> > + if (vaddr < vma->vm_start || vaddr > vma->vm_end) {
> > + /* Not in this vma */
> > + mmput(mm);
> > + continue;
> > + }
> > + tsk = get_mm_owner(mm);
> > + if (tsk && vaddr > TASK_SIZE_OF(tsk)) {
> > + /*
> > + * We cannot have a virtual address that is
> > + * greater than TASK_SIZE_OF(tsk)
> > + */
> > + put_task_struct(tsk);
> > + mmput(mm);
> > + continue;
> > + }
> > + put_task_struct(tsk);
> > + mm->uprobes_vaddr = (unsigned long) vaddr;
> > + list_add(&mm->uprobes_list, &try_list);
> > + }
>
> This still falls flat on its face when there's multiple maps of the same
> text in one mm.
>

To address this we will use a uprobe_info structure.

struct uprobe_info {
unsigned long uprobes_vaddr;
struct mm_struct *mm;
struct list_head uprobes_list;
};

and remove the uprobes_list and uprobes_vaddr entries from mm structure.

the uprobe_info structures will be created in the vma_prio_tree_foreach
loop as and when required. Since we now have i_mmap_mutex, allocating this
uprobe_info structure as when required should be okay.

Agree?

--
Thanks and Regards
Srikar