On Wed, Oct 21, 2020 at 08:39:48AM +0800, Leo Yan wrote:
> When execute command "perf lock report", it hits failure and outputs log
> as follows:
>
> perf: builtin-lock.c:623: report_lock_release_event: Assertion
> `!(seq->read_count < 0)' failed.
> Aborted
>
> This is an imbalance issue. The locking sequence structure
> "lock_seq_stat" contains the reader counter and it is used to check if
> the locking sequence is balance or not between acquiring and releasing.
>
> If the tool wrongly frees "lock_seq_stat" when "read_count" isn't zero,
> the "read_count" will be reset to zero when allocate a new structure at
> the next time; thus it causes the wrong counting for reader and finally
> results in imbalance issue.
>
> To fix this issue, if detects "read_count" is not zero (means still
> have read user in the locking sequence), goto the "end" tag to skip
> freeing structure "lock_seq_stat".
>
> Fixes: e4cef1f65061 ("perf lock: Fix state machine to recognize lock
> sequence")
> Signed-off-by: Leo Yan <[email protected]>
> ---
> tools/perf/builtin-lock.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
> index 5cecc1ad78e1..a2f1e53f37a7 100644
> --- a/tools/perf/builtin-lock.c
> +++ b/tools/perf/builtin-lock.c
> @@ -621,7 +621,7 @@ static int report_lock_release_event(struct evsel *evsel,
> case SEQ_STATE_READ_ACQUIRED:
> seq->read_count--;
> BUG_ON(seq->read_count < 0);
> - if (!seq->read_count) {
> + if (seq->read_count) {
> ls->nr_release++;
it seems ok, but I fail to see what's nr_release for
the point is just to skip the removal of seq right?
jirka
> goto end;
> }
> --
> 2.17.1
>
