Commit a7ef9b28 authored Jul 25, 2020 by Chris Wilson Committed by Ingo Molnar Jul 25, 2020

locking/lockdep: Fix overflow in presentation of average lock-time



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@chris-wilson.co.uk>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20200725185110.11588-1-chris@chris-wilson.co.uk

parent 23ee3e4e

kernel/locking/lockdep_proc.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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)

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