From 891c39708144bbe401b4aa151bffd0fe41b1dafd Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 29 Jul 2012 20:22:40 +0200 Subject: [PATCH] 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 Acked-by: Srikar Dronamraju Cc: Anton Arapov Cc: Srikar Dronamraju Link: http://lkml.kernel.org/r/20120729182240.GA20352@redhat.com Signed-off-by: Ingo Molnar --- kernel/events/uprobes.c | 103 +++++++++++++++++++--------------------- 1 file changed, 50 insertions(+), 53 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index fb961d5e205c..2ef123306183 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -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); - - if (uprobe->inode == inode) - close_node = n; + struct uprobe *u = rb_entry(n, struct uprobe, rb_node); - 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; - - spin_lock_irqsave(&uprobes_treelock, flags); - - n = find_least_offset_node(inode); + struct rb_node *n, *t; + struct uprobe *u; - for (; n; n = rb_next(n)) { - uprobe = rb_entry(n, struct uprobe, rb_node); - if (uprobe->inode != inode) - break; + INIT_LIST_HEAD(head); + min = ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + start - vma->vm_start; + max = min + (end - start) - 1; - list_add(&uprobe->pending_list, head); - atomic_inc(&uprobe->ref); + 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); } @@ -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)); -- 2.20.1