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Message-ID: <50399556C9727B4D88A595C8584AAB3752604844@GSjpTKYDCembx32.service.hitachi.net>
Date: Thu, 5 Nov 2015 14:08:48 +0000
From: 平松雅巳 / HIRAMATU,MASAMI
<masami.hiramatsu.pt@...achi.com>
To: "'Wang Nan'" <wangnan0@...wei.com>,
"acme@...nel.org" <acme@...nel.org>,
"namhyung@...nel.org" <namhyung@...nel.org>
CC: "lizefan@...wei.com" <lizefan@...wei.com>,
"pi3orama@....com" <pi3orama@....com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"jolsa@...nel.org" <jolsa@...nel.org>,
Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: RE: [PATCH 2/2] perf tools: Fix find_perf_probe_point_from_map()
which incorrectly returns success
From: Wang Nan [mailto:wangnan0@...wei.com]
>
>It is possible that find_perf_probe_point_from_map() fails to find
>symbol but still returns 0 because of an small error when coding:
>find_perf_probe_point_from_map() set 'ret' to error code at first,
>but also use it to hold return value of
>kernel_get_symbol_address_by_name().
OK, I didn't expect that there is a symbol which can be found by
kernel_get_symbol_address_by_name() but not by __find_kernel_function()...
Would you have any example of the error?
>
>This patch resets 'ret' to error even kernel_get_symbol_address_by_name()
>success, so if !sym, the whole function returns error correctly.
Hmm, that sounds tricky. I'd rather like to add *psym to kernel_get_symbol_address_by_name()
to save symbol and don't use __find_kernel_function() instead.
Thank you,
>
>Signed-off-by: Wang Nan <wangnan0@...wei.com>
>Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
>Cc: Jiri Olsa <jolsa@...nel.org>
>Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
>Cc: Namhyung Kim <namhyung@...nel.org>
>---
> tools/perf/util/probe-event.c | 3 +++
> 1 file changed, 3 insertions(+)
>
>diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
>index b51a8bf..e659c4f 100644
>--- a/tools/perf/util/probe-event.c
>+++ b/tools/perf/util/probe-event.c
>@@ -1905,6 +1905,9 @@ static int find_perf_probe_point_from_map(struct probe_trace_point *tp,
> sym = __find_kernel_function(addr, &map);
> }
> }
>+
>+ /* ret may has be overwritten so reset it */
>+ ret = -ENOENT;
> if (!sym)
> goto out;
>
>--
>1.8.3.4
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