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SubjectRe: [PATCH 5/8] trace_uprobe: Support SDT markers having reference count (semaphore)
On 03/13, Ravi Bangoria wrote:
>
> @@ -1053,6 +1056,9 @@ int uprobe_mmap(struct vm_area_struct *vma)
> struct uprobe *uprobe, *u;
> struct inode *inode;
>
> + if (uprobe_mmap_callback)
> + uprobe_mmap_callback(vma);
> +
> if (no_uprobe_events() || !valid_vma(vma, true))
> return 0;

probe_event_enable() does

uprobe_register();
/* WINDOW */
sdt_increment_ref_ctr();

what if uprobe_mmap() is called in between? The counter(s) in this vma
will be incremented twice, no?

> +static struct vm_area_struct *
> +sdt_find_vma(struct mm_struct *mm, struct trace_uprobe *tu)
> +{
> + struct vm_area_struct *tmp;
> +
> + for (tmp = mm->mmap; tmp != NULL; tmp = tmp->vm_next)
> + if (sdt_valid_vma(tu, tmp))
> + return tmp;
> +
> + return NULL;

I can't understand the logic... Lets ignore sdt_valid_vma() for now.
The caller has uprobe_map_info, why it can't simply do
vma = find_vma(uprobe_map_info->vaddr)? and then check sdt_valid_vma().

Oleg.

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