linux-kernel - [PATCH] perfcounter: fix zero or negative refresh delay

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Date:	Fri,  5 Jun 2009 19:31:01 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Mike Galbraith <efault@....de>,
	Paul Mackerras <paulus@...ba.org>,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: [PATCH] perfcounter: fix zero or negative refresh delay

If perf top is executed with a zero value for the refresh rate,
we get a division by zero exception while computing samples_per_sec.

Also a zero refresh rate is not possible, neither do we want to
accept negative values.

[ Impact: fix division by zero in perf top ]

Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Mike Galbraith <efault@....de>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Corey Ashford <cjashfor@...ux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@...hat.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
---
 Documentation/perf_counter/builtin-top.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/Documentation/perf_counter/builtin-top.c b/Documentation/perf_counter/builtin-top.c
index ff7e13c..b2f480b 100644
--- a/Documentation/perf_counter/builtin-top.c
+++ b/Documentation/perf_counter/builtin-top.c
@@ -693,6 +693,9 @@ int cmd_top(int argc, const char **argv, const char *prefix)
 		event_id[0] = 0;
 	}
 
+	if (delay_secs < 1)
+		delay_secs = 1;
+
 	for (counter = 0; counter < nr_counters; counter++) {
 		if (event_count[counter])
 			continue;
-- 
1.6.2.3

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