Messages in this thread | | | Date | Tue, 30 Sep 2014 10:58:14 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/2] Use faster check for modules in backtrace on 64bit |
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On Mon, Sep 29, 2014 at 10:30:23PM +0200, Andi Kleen wrote: > On Mon, Sep 29, 2014 at 08:21:45AM -0700, Andi Kleen wrote: > > On Mon, Sep 29, 2014 at 01:42:12PM +0200, Peter Zijlstra wrote: > > > On Fri, Sep 26, 2014 at 04:31:16PM -0700, Andi Kleen wrote: > > > > > > > > This has the (small) potential to get a false positive on a pointer to a > > > > data segment in a module. However since we also use the frame pointer > > > > chain as initial sanity check I think the danger of this is very low. > > > > > > > > > > So this has come up several times; and the answer has always been, why > > > not make the __module_address() thing a rb-tree instead of a linear > > > loop. So I suppose I'll ask that again, why not? > > > > Why do things complicated, if they can be done simple too? > > Also I investigated it now, but we don't have RCU support for rbtrees. > So it would need some kind of locking for the reader, which is a show > stopper.
Nah, we can trivially do that with a seqlock. Not read side locking required in the normal case.
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