Hello Namhyung!
On 11/21/2025 12:48 AM, Namhyung Kim wrote:
> Save samples with deferred callchains in a separate list and deliver
> them after merging the user callchains. If users don't want to merge
> they can set tool->merge_deferred_callchains to false to prevent the
> behavior.
> diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
> +int sample__merge_deferred_callchain(struct perf_sample *sample_orig,
> + struct perf_sample *sample_callchain)
> +{
> + u64 nr_orig = sample_orig->callchain->nr - 1;
> + u64 nr_deferred = sample_callchain->callchain->nr;
> + struct ip_callchain *callchain;
> +
> + if (sample_orig->callchain->nr < 2) {
> + sample_orig->deferred_callchain = false;
> + return -EINVAL;
> + }
> +
> + callchain = calloc(1 + nr_orig + nr_deferred, sizeof(u64));
> + if (callchain == NULL) {
> + sample_orig->deferred_callchain = false;
> + return -ENOMEM;
> + }
> +
> + callchain->nr = nr_orig + nr_deferred;
> + /* copy original including PERF_CONTEXT_USER_DEFERRED (but the cookie)
> */
> + memcpy(callchain->ips, sample_orig->callchain->ips, nr_orig *
> sizeof(u64));
> + /* copy deferred user callchains */
> + memcpy(&callchain->ips[nr_orig], sample_callchain->callchain->ips,
> + nr_deferred * sizeof(u64));
> +
> + sample_orig->callchain = callchain;
Hope you don't mind my naive question, as I don't have a clue about perf:
Doesn't the sample_orig->callchain storage need to be free'd prior to
assigning the newly allocated one? Or is that just part of a large
block that got allocated in one piece? How is then the one allocated
here ever free'd?
> + return 0;
> +}
Thanks and regards,
Jens
--
Jens Remus
Linux on Z Development (D3303)
+49-7031-16-1128 Office
[email protected]
IBM
IBM Deutschland Research & Development GmbH; Vorsitzender des Aufsichtsrats:
Wolfgang Wendt; Geschäftsführung: David Faller; Sitz der Gesellschaft:
Böblingen; Registergericht: Amtsgericht Stuttgart, HRB 243294
IBM Data Privacy Statement: https://www.ibm.com/privacy/
