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Re: [patch 1/2] [BUG]kallsyms_lookup_name should return the text addres
- From: "Randy.Dunlap" <rdunlap at xenotime dot net>
- To: Keith Owens <kaos at sgi dot com>
- Cc: Keshavamurthy Anil S <anil dot s dot keshavamurthy at intel dot com>, Paulo Marques <pmarques at grupopie dot com>, Linux Kernel <linux-kernel at vger dot kernel dot org>, akpm at osdl dot org, tony dot luck at intel dot com, Systemtap <systemtap at sources dot redhat dot com>, Jim Keniston <jkenisto at us dot ibm dot com>
- Date: Tue, 10 Jan 2006 16:07:55 -0800 (PST)
- Subject: Re: [patch 1/2] [BUG]kallsyms_lookup_name should return the text addres
- References: <19866.1136937775@ocs3.ocs.com.au>
On Wed, 11 Jan 2006, Keith Owens wrote:
> Keshavamurthy Anil S (on Tue, 10 Jan 2006 15:29:05 -0800) wrote:
> >On Wed, Jan 11, 2006 at 10:11:26AM +1100, Keith Owens wrote:
> >> Keshavamurthy Anil S (on Tue, 10 Jan 2006 13:07:37 -0800) wrote:
> >> >On Tue, Jan 10, 2006 at 08:45:02PM +0000, Paulo Marques wrote:
> >> >But my [patch 2/2] speeds up the lookup and that can go in, I think.
> >> >Please ack that patch if you think so.
> >>
> >> Your second patch changes the behaviour of kallsyms lookup w.r.t
> >> duplicate symbols.
> >With this send patch, kallsyms lookup first finds
> >the real text address which is what we want. If you consider
> >this as the change in behaviour, what is the negetive effect of this
> >I am unable to get it.
>
> Local symbols can be (and are) duplicated in the kernel code, and these
> duplicate symbols can appear in modules. Changing the list order of
> loaded modules also changes which version of a duplicated symbol is
> returned by the kallsyms code. Not a big deal, but annoying enough to
> say "don't change the module list order".
>
> Changing the thread slightly, kallsyms_lookup_name() has never coped
> with duplicate local symbols and it cannot do so without changing its
> API, and all its callers. For debugging purposes, it would be nicer if
> the kernel did not have any duplicate symbols. Perhaps some kernel
> janitor would like to take that task on.
Jesper Juhl was doing some -Wshadow patches. Would that detect
duplicate symbols?
--
~Randy [sees nothing wrong with dup. local symbols, except for debugging]