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Date: Thu, 15 Feb 2018 11:27:11 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Jiri Olsa <jolsa@kernel.org>
Cc: lkml <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>, David Ahern <dsahern@gmail.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Subject: Re: [PATCH 9/9] perf tests: Use arch__compare_symbol_names to
 compare symbols
Message-ID: <20180215142711.GH22818@kernel.org>
References: <20180215122635.24029-1-jolsa@kernel.org>
 <20180215122635.24029-10-jolsa@kernel.org>
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Em Thu, Feb 15, 2018 at 01:26:35PM +0100, Jiri Olsa escreveu:
> The symbol search called by machine__find_kernel_symbol_by_name
> is using internally arch__compare_symbol_names function to compare
> 2 symbol names, because different archs have different ways of
> comparing symbols. Mostly for skipping '.' prefixes and similar.
> 
> In test 1 when we try to find matching symbols in kallsyms and
> vmlinux, by address and by symbol name. When either is found
> we compare the pair symbol names  by simple strcmp, which is not
> good enough for reasons explained in previous paragraph.
> 
> On powerpc this can cause lockup, because even thought we found
> the pair, the compared names are different and don't match
> simple strcmp. Following code path is executed, that leads
> to lockup:

Added a:

    Fixes: 031b84c407c3 ("perf probe ppc: Enable matching against dot symbols automatically")

And CCed Naveen, the author of that patch, so that gets notified of this
fix.

Thanks,

- Arnaldo