| Subject | Re: [PATCH v5 3.1.0-rc4-tip 1/26] uprobes: Auxillary routines to insert, find, delete uprobes | From | Peter Zijlstra <> | Date | Mon, 26 Sep 2011 13:18:40 +0200 |
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On Tue, 2011-09-20 at 17:29 +0530, Srikar Dronamraju wrote: > +static struct uprobe *__insert_uprobe(struct uprobe *uprobe) > +{ > + struct rb_node **p = &uprobes_tree.rb_node; > + struct rb_node *parent = NULL; > + struct uprobe *u; > + int match; > + > + while (*p) { > + parent = *p; > + u = rb_entry(parent, struct uprobe, rb_node); > + match = match_uprobe(uprobe, u); > + if (!match) { > + atomic_inc(&u->ref); > + return u; > + } > + > + if (match < 0) > + p = &parent->rb_left; > + else > + p = &parent->rb_right; > + > + } > + u = NULL; > + rb_link_node(&uprobe->rb_node, parent, p); > + rb_insert_color(&uprobe->rb_node, &uprobes_tree); > + /* get access + drop ref */ > + atomic_set(&uprobe->ref, 2); > + return u; > +}
If you ever want to make a 'lockless' lookup work you need to set the refcount of the new object before its fully visible, instead of after.
Now much of a problem now since its fully serialized by that uprobes_treelock thing.
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