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uprobes: Teach build_probe_list() to consider the range 

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.

While at it, shift INIT_LIST_HEAD(tmp_list) into
build_probe_list().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar.vnet.ibm.com>
Cc: Anton Arapov <anton@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20120729182240.GA20352@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Oleg Nesterov 2012-07-29 20:22:40 +02:00 committed by Ingo Molnar
parent 89133786f9
commit 891c397081
1 changed files with 50 additions and 53 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

103
kernel/events/uprobes.c
View File

@ -939,59 +939,66 @@ void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consume
put_uprobe(uprobe);
}
/*
* Of all the nodes that correspond to the given inode, return the node
* with the least offset.
*/
static struct rb_node *find_least_offset_node(struct inode *inode)
static struct rb_node *
find_node_in_range(struct inode *inode, loff_t min, loff_t max)
{
struct uprobe u = { .inode = inode, .offset = 0};
struct rb_node *n = uprobes_tree.rb_node;
struct rb_node *close_node = NULL;
struct uprobe *uprobe;
int match;
while (n) {
uprobe = rb_entry(n, struct uprobe, rb_node);
match = match_uprobe(&u, uprobe);
struct uprobe *u = rb_entry(n, struct uprobe, rb_node);
if (uprobe->inode == inode)
close_node = n;
if (!match)
return close_node;
if (match < 0)
if (inode < u->inode) {
n = n->rb_left;
else
} 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 close_node;
return n;
}
/*
* For a given inode, build a list of probes that need to be inserted.
* 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 list_head *head)
static void build_probe_list(struct inode *inode,
struct vm_area_struct *vma,
unsigned long start, unsigned long end,
struct list_head *head)
{
struct uprobe *uprobe;
loff_t min, max;
unsigned long flags;
struct rb_node *n;
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_least_offset_node(inode);
for (; n; n = rb_next(n)) {
uprobe = rb_entry(n, struct uprobe, rb_node);
if (uprobe->inode != inode)
break;
list_add(&uprobe->pending_list, head);
atomic_inc(&uprobe->ref);
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);
}
@ -1021,9 +1028,8 @@ int uprobe_mmap(struct vm_area_struct *vma)
if (!inode)
return 0;
INIT_LIST_HEAD(&tmp_list);
mutex_lock(uprobes_mmap_hash(inode));
build_probe_list(inode, &tmp_list);
build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list);
ret = 0;
count = 0;
@ -1032,11 +1038,6 @@ int uprobe_mmap(struct vm_area_struct *vma)
if (!ret) {
loff_t vaddr = vma_address(vma, uprobe->offset);
if (vaddr < vma->vm_start || vaddr >= vma->vm_end) {
put_uprobe(uprobe);
continue;
}
ret = install_breakpoint(uprobe, vma->vm_mm, vma, vaddr);
/*
* We can race against uprobe_register(), see the
@ -1092,21 +1093,17 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon
if (!inode)
return;
INIT_LIST_HEAD(&tmp_list);
mutex_lock(uprobes_mmap_hash(inode));
build_probe_list(inode, &tmp_list);
build_probe_list(inode, vma, start, end, &tmp_list);
list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
loff_t vaddr = vma_address(vma, uprobe->offset);
if (vaddr >= start && vaddr < end) {
/*
* An unregister could have removed the probe before
* unmap. So check before we decrement the count.
*/
if (is_swbp_at_addr(vma->vm_mm, vaddr) == 1)
atomic_dec(&vma->vm_mm->uprobes_state.count);
}
/*
* An unregister could have removed the probe before
* unmap. So check before we decrement the count.
*/
if (is_swbp_at_addr(vma->vm_mm, vaddr) == 1)
atomic_dec(&vma->vm_mm->uprobes_state.count);
put_uprobe(uprobe);
}
mutex_unlock(uprobes_mmap_hash(inode));