Re: [PATCH] perf inject: correct event attribute sizes

Mark Rutland
2020-08-26T11:41:24Z

On Wed, Aug 26, 2020 at 10:42:04AM +0100, Al Grant wrote:
> When perf inject reads a perf.data file from an older version of perf,
> it writes event attributes into the output with the original size field,
> but lays them out as if they had the size currently used. Readers see
> a corrupt file. Update the size field to match the layout.
>
> From: Denis Nikitin <denik@google.com>
> Signed-off-by: Al Grant <al.grant@foss.arm.com>

Did Denis write this patch?

If so, we need an S-o-B line from them.

Mark.

> tools/perf/util/header.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index 9cf4efdcbbbd..762eb94bd532 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -3326,6 +3326,14 @@ int perf_session__write_header(struct
> perf_session *session,
> attr_offset = lseek(ff.fd, 0, SEEK_CUR);
>
> evlist__for_each_entry(evlist, evsel) {
> + if (evsel->core.attr.size < sizeof(evsel->core.attr)) {
> + /*
> + * We are likely in "perf inject" and have read +
> * from an older file. Update attr size so that
> + * reader gets the right offset to the ids.
> + */
> + evsel->core.attr.size = sizeof(evsel->core.attr);
> + }
> f_attr = (struct perf_file_attr){
> .attr = evsel->core.attr,
> .ids = {