linux-kernel - [PATCH 3.19.y-ckt 105/107] perf hists browser: Take the --comm, --dsos, etc filters into account

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Message-Id: <1438811379-384-106-git-send-email-kamal@canonical.com>
Date:	Wed,  5 Aug 2015 14:49:37 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Adrian Hunter <adrian.hunter@...el.com>,
	Borislav Petkov <bp@...e.de>, David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Jiri Olsa <jolsa@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Stephane Eranian <eranian@...gle.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 105/107] perf hists browser: Take the --comm, --dsos, etc filters into account

3.19.8-ckt5 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Arnaldo Carvalho de Melo <acme@...hat.com>

commit 9c0fa8dd3d58de8b688fda758eea1719949c7f0a upstream.

At some point:

  commit 2c86c7ca7606
  Author: Namhyung Kim <namhyung@...nel.org>
  Date:   Mon Mar 17 18:18:54 2014 -0300

    perf report: Merge al->filtered with hist_entry->filtered

We stopped dropping samples for things filtered via the --comms, --dsos,
--symbols, etc, i.e. things marked as filtered in the symbol resolution
routines (thread__find_addr_map(), perf_event__preprocess_sample(),
etc).

But then, in:

  commit 268397cb2a47
  Author: Namhyung Kim <namhyung@...nel.org>
  Date:   Tue Apr 22 14:49:31 2014 +0900

    perf top/tui: Update nr_entries properly after a filter is applied

We don't take into account entries that were filtered in
perf_event__preprocess_sample() and friends, which leads to
inconsistency in the browser seek routines, that expects the number of
hist_entry->filtered entries to match what it thinks is the number of
unfiltered, browsable entries.

So, for instance, when we do:

  perf top --symbols ___non_existent_symbol___

the hist_browser__nr_entries() routine thinks there are no filters in
place, uses the hists->nr_entries but all entries are filtered, leading
to a segfault.

Tested with:

   perf top --symbols malloc,free --percentage=relative

Freezing, by pressing 'f', at any time and doing the math on the
percentages ends up with 100%, ditto for:

   perf top --dsos libpthread-2.20.so,libxul.so --percentage=relative

Both were segfaulting, all fixed now.

More work needed to do away with checking if filters are in place, we
should just use the nr_non_filtered_samples counter, no need to
conditionally use it or hists.nr_filter, as what the browser does is
just show unfiltered stuff. An audit of how it is being accounted is
needed, this is the minimal fix.

Reported-by: Michael Petlan <mpetlan@...hat.com>
Fixes: 268397cb2a47 ("perf top/tui: Update nr_entries properly after a filter is applied")
Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Borislav Petkov <bp@...e.de>
Cc: David Ahern <dsahern@...il.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Stephane Eranian <eranian@...gle.com>
Link: http://lkml.kernel.org/n/tip-6w01d5q97qk0d64kuojme5in@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 tools/perf/ui/browsers/hists.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index 788506e..0ccdec0 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -45,7 +45,7 @@ static struct rb_node *hists__filter_entries(struct rb_node *nd,
 
 static bool hist_browser__has_filter(struct hist_browser *hb)
 {
-	return hists__has_filter(hb->hists) || hb->min_pcnt;
+	return hists__has_filter(hb->hists) || hb->min_pcnt || symbol_conf.has_filter;
 }
 
 static u32 hist_browser__nr_entries(struct hist_browser *hb)
-- 
1.9.1

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