On 07/09, Oleg Nesterov wrote:
>
> Currently build_probe_list() builds the list of all uprobes attached
> to the given inode, and the caller should filter out those who don't
> fall into the [start,end) range, this is sub-optimal.
>
> This patch turns find_least_offset_node() into find_node_in_range()
> which returns the first node inside the [min,max] range, and changes
> build_probe_list() to use this node as a starting point for rb_prev()
> and rb_next() to find all other nodes the caller needs. The resulting
> list is no longer sorted but we do not care.
>
> This can speed up both build_probe_list() and the callers, but there
> is another reason to introduce find_node_in_range(). It can be used
> to figure out whether the given vma has uprobes or not, this will be
> needed soon.
I guess it is not easy to read this patch without applying, I am sending
the code to simplify the review.
----------------------------------------------------------------------
static struct rb_node *
find_node_in_range(struct inode *inode, loff_t min, loff_t max)
{
struct rb_node *n = uprobes_tree.rb_node;
while (n) {
struct uprobe *u = rb_entry(n, struct uprobe, rb_node);
if (inode < u->inode) {
n = n->rb_left;
} else if (inode > u->inode) {
n = n->rb_right;
} else {
if (max < u->offset)
n = n->rb_left;
else if (min > u->offset)
n = n->rb_right;
else
break;
}
}
return n;
}
/*
* For a given range in vma, build a list of probes that need to be inserted.
*/
static void build_probe_list(struct inode *inode,
struct vm_area_struct *vma,
unsigned long start, unsigned long end,
struct list_head *head)
{
loff_t min, max;
unsigned long flags;
struct rb_node *n, *t;
struct uprobe *u;
INIT_LIST_HEAD(head);
min = ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + start - vma->vm_start;
max = min + (end - start) - 1;
spin_lock_irqsave(&uprobes_treelock, flags);
n = find_node_in_range(inode, min, max);
if (n) {
for (t = n; t; t = rb_prev(t)) {
u = rb_entry(t, struct uprobe, rb_node);
if (u->inode != inode || u->offset < min)
break;
list_add(&u->pending_list, head);
atomic_inc(&u->ref);
}
for (t = n; (t = rb_next(t)); ) {
u = rb_entry(t, struct uprobe, rb_node);
if (u->inode != inode || u->offset > max)
break;
list_add(&u->pending_list, head);
atomic_inc(&u->ref);
}
}
spin_unlock_irqrestore(&uprobes_treelock, flags);
}
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