Commit-ID: d988ff94c1074c4c914235c8591bcceafb585ecf
Gitweb: http://git.kernel.org/tip/d988ff94c1074c4c914235c8591bcceafb585ecf
Author: Steven Rostedt <srostedt@xxxxxxxxxx>
AuthorDate: Fri, 8 May 2009 11:03:57 -0400
Committer: Steven Rostedt <rostedt@xxxxxxxxxxx>
CommitDate: Mon, 11 May 2009 13:22:26 -0400
ring-buffer: check for divide by zero in ring-buffer-benchmark
Although we check if "missed" is not zero, we divide by hit + missed,
and the addition can possible overflow and become a divide by zero.
This patch checks for this case, and will report it when it happens
then modify "hit" to make the calculation be non zero.
[ Impact: prevent possible divide by zero in ring-buffer-benchmark ]
Reported-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
kernel/trace/ring_buffer_benchmark.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/kernel/trace/ring_buffer_benchmark.c b/kernel/trace/ring_buffer_benchmark.c
index 7d3aef9..8d68e14 100644
--- a/kernel/trace/ring_buffer_benchmark.c
+++ b/kernel/trace/ring_buffer_benchmark.c
@@ -294,6 +294,12 @@ static void ring_buffer_producer(void)
pr_info("Total iterations per millisec: %ld\n", hit + missed);
+ /* it is possible that hit + missed will overflow and be zero */
+ if (!(hit + missed)) {
+ pr_info("hit + missed overflowed and totalled zero!\n");
+ hit--; /* make it non zero */
+ }
+
/* Caculate the average time in nanosecs */
avg = NSEC_PER_MSEC / (hit + missed);
pr_info("%ld ns per entry\n", avg);
--
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