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| author | Steven Rostedt | 2009-05-08 17:03:57 +0200 |
|---|---|---|
| committer | Steven Rostedt | 2009-05-11 19:22:26 +0200 |
| commit | d988ff94c1074c4c914235c8591bcceafb585ecf (patch) | |
| tree | 46dc84aa84e04ae92cd66ed5cbf7a55452dcdb1c /kernel/trace/ring_buffer_benchmark.c | |
| parent | ring-buffer: replace constants with time macros in ring-buffer-benchmark (diff) | |
| download | kernel-qcow2-linux-d988ff94c1074c4c914235c8591bcceafb585ecf.tar.gz kernel-qcow2-linux-d988ff94c1074c4c914235c8591bcceafb585ecf.tar.xz kernel-qcow2-linux-d988ff94c1074c4c914235c8591bcceafb585ecf.zip | |
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@linux-foundation.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/ring_buffer_benchmark.c')
| -rw-r--r-- | 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 7d3aef93c49f..8d68e149a8b3 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); |