[PATCH 01/36] locking/lockdep: Fix overflow in presentation of average lock-time
Chris Wilson
chris at chris-wilson.co.uk
Sun Jul 26 10:09:05 UTC 2020
Though the number of lock-acquisitions is tracked as unsigned long, this
is passed as the divisor to div_s64() which interprets it as a s32,
giving nonsense values with more than 2 billion acquisitons. E.g.
acquisitions holdtime-min holdtime-max holdtime-total holdtime-avg
-------------------------------------------------------------------------
2350439395 0.07 353.38 649647067.36 0.-32
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Peter Zijlstra <peterz at infradead.org>
Cc: Ingo Molnar <mingo at redhat.com>
Cc: Will Deacon <will at kernel.org>
---
kernel/locking/lockdep_proc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c
index 5525cd3ba0c8..02ef87f50df2 100644
--- a/kernel/locking/lockdep_proc.c
+++ b/kernel/locking/lockdep_proc.c
@@ -423,7 +423,7 @@ static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
seq_time(m, lt->min);
seq_time(m, lt->max);
seq_time(m, lt->total);
- seq_time(m, lt->nr ? div_s64(lt->total, lt->nr) : 0);
+ seq_time(m, lt->nr ? div64_u64(lt->total, lt->nr) : 0);
}
static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
--
2.20.1
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