Messages in this thread | | | Date | Mon, 26 Sep 2011 17:32:29 +0530 | From | Srikar Dronamraju <> | Subject | Re: [PATCH v5 3.1.0-rc4-tip 1/26] uprobes: Auxillary routines to insert, find, delete uprobes |
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* Peter Zijlstra <peterz@infradead.org> [2011-09-26 13:18:40]:
> 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. >
Agree,
> Now much of a problem now since its fully serialized by that > uprobes_treelock thing. >
Will stick with this for now; If and when we do a lockless lookup we could fix this.
-- Thanks and Regards Srikar
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