Subject: Re: linux-next: manual merge of the perf tree with the origin tree

From: Namhyung Kim <[email-masked]>
Date: Mon, 17 Jun 2024 20:21:30 -0700

Hello,

On Mon, Jun 17, 2024 at 05:23:02PM +0100, Mark Brown wrote:
> Hi all,
> 
> Today's linux-next merge of the perf tree got a conflict in:
> 
>   tools/perf/builtin-record.c
> 
> between commit:
> 
>   5b3cde198878b ("Revert "perf record: Reduce memory for recording PERF_RECORD_LOST_SAMPLES event"")
> 
> from the origin tree and commit:
> 
>   6c1785cd75ef5 ("perf record: Ensure space for lost samples")
> 
> from the perf tree.
> 
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging.  You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.

Thanks for doing this!  The resolution looks good.  I plan to merge
the revert and other fixes in the v6.10 tree into perf-tools-next
before v6.11 window open.

Thanks,
Namhyung

> 
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 0a8ba1323d64b..019305b94e5fc 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -1926,7 +1926,7 @@ static void __record__save_lost_samples(struct record *rec, struct evsel *evsel,
>  static void record__read_lost_samples(struct record *rec)
>  {
>  	struct perf_session *session = rec->session;
> -	struct perf_record_lost_samples *lost = NULL;
> +	struct perf_record_lost_samples_and_ids lost;
>  	struct evsel *evsel;
>  
>  	/* there was an error during record__open */
> @@ -1951,19 +1951,13 @@ static void record__read_lost_samples(struct record *rec)
>  
>  				if (perf_evsel__read(&evsel->core, x, y, &count) < 0) {
>  					pr_debug("read LOST count failed\n");
> -					goto out;
> +					return;
>  				}
>  
>  				if (count.lost) {
> -					if (!lost) {
> -						lost = zalloc(PERF_SAMPLE_MAX_SIZE);
> -						if (!lost) {
> -							pr_debug("Memory allocation failed\n");
> -							return;
> -						}
> -						lost->header.type = PERF_RECORD_LOST_SAMPLES;
> -					}
> -					__record__save_lost_samples(rec, evsel, lost,
> +					memset(&lost.lost, 0, sizeof(lost));
> +					lost.lost.header.type = PERF_RECORD_LOST_SAMPLES;
> +					__record__save_lost_samples(rec, evsel, &lost.lost,
>  								    x, y, count.lost, 0);
>  				}
>  			}
> @@ -1971,20 +1965,12 @@ static void record__read_lost_samples(struct record *rec)
>  
>  		lost_count = perf_bpf_filter__lost_count(evsel);
>  		if (lost_count) {
> -			if (!lost) {
> -				lost = zalloc(PERF_SAMPLE_MAX_SIZE);
> -				if (!lost) {
> -					pr_debug("Memory allocation failed\n");
> -					return;
> -				}
> -				lost->header.type = PERF_RECORD_LOST_SAMPLES;
> -			}
> -			__record__save_lost_samples(rec, evsel, lost, 0, 0, lost_count,
> +			memset(&lost.lost, 0, sizeof(lost));
> +			lost.lost.header.type = PERF_RECORD_LOST_SAMPLES;
> +			__record__save_lost_samples(rec, evsel, &lost.lost, 0, 0, lost_count,
>  						    PERF_RECORD_MISC_LOST_SAMPLES_BPF);
>  		}
>  	}
> -out:
> -	free(lost);
>  }
>  
>  static volatile sig_atomic_t workload_exec_errno;
> @@ -3196,7 +3182,7 @@ static int switch_output_setup(struct record *rec)
>  	unsigned long val;
>  
>  	/*
> -	 * If we're using --switch-output-events, then we imply its 
> +	 * If we're using --switch-output-events, then we imply its
>  	 * --switch-output=signal, as we'll send a SIGUSR2 from the side band
>  	 *  thread to its parent.
>  	 */