perf evlist: Refactor evlist__scnprintf_evsels()

Switch output to using a strbuf so the storage can be resized.

Add a maximum size argument to avoid too much output that may happen for
uncore events.

Rename as scnprintf is no longer used.

Committer testing:

  With the patch applied:

  root@number:~# perf probe -x ~/bin/perf evlist__format_evsels
  Added new event:
    probe_perf:evlist_format_evsels (on evlist__format_evsels in /home/acme/bin/perf)

  You can now use it in all perf tools, such as:

  	perf record -e probe_perf:evlist_format_evsels -aR sleep 1

  root@number:~# perf probe -l
    probe_perf:evlist_format_evsels (on evlist__format_evsels@util/evlist.c in /home/acme/bin/perf)
  root@number:~# perf trace -e probe_perf:*/max-stack=10/ perf record -e cycles,instructions,cache-misses /tmp/bla
  Failed to collect 'cycles,instructions,cache-misses' for the '/tmp/bla' workload: Permission denied
       0.000 perf/3893011 probe_perf:evlist_format_evsels(__probe_ip: 6183397)
                                         evlist__format_evsels (/home/acme/bin/perf)
                                         __cmd_record (/home/acme/bin/perf)
                                         cmd_record (/home/acme/bin/perf)
                                         run_builtin (/home/acme/bin/perf)
                                         handle_internal_command (/home/acme/bin/perf)
                                         run_argv (/home/acme/bin/perf)
                                         main (/home/acme/bin/perf)
                                         __libc_start_call_main (/usr/lib64/libc.so.6)
                                         __libc_start_main@@GLIBC_2.34 (/usr/lib64/libc.so.6)
                                         _start (/home/acme/bin/perf)
  root@number:~#

Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dominique Martinet <asmadeus@codewreck.org>
Cc: Dr. David Alan Gilbert <linux@treblig.org>
Cc: Howard Chu <howardchu95@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Levi Yun <yeoreum.yun@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Weilin Wang <weilin.wang@intel.com>
Link: https://lore.kernel.org/r/20250402201549.4090305-4-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 8898357325cf..52cebacc19a7 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -51,6 +51,7 @@
 #include "util/clockid.h"
 #include "util/off_cpu.h"
 #include "util/bpf-filter.h"
+#include "util/strbuf.h"
 #include "asm/bug.h"
 #include "perf.h"
 #include "cputopo.h"
@@ -2791,13 +2792,15 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 		record__auxtrace_snapshot_exit(rec);
 
 	if (forks && workload_exec_errno) {
-		char msg[STRERR_BUFSIZE], strevsels[2048];
+		char msg[STRERR_BUFSIZE];
 		const char *emsg = str_error_r(workload_exec_errno, msg, sizeof(msg));
+		struct strbuf sb = STRBUF_INIT;
 
-		evlist__scnprintf_evsels(rec->evlist, sizeof(strevsels), strevsels);
+		evlist__format_evsels(rec->evlist, &sb, 2048);
 
 		pr_err("Failed to collect '%s' for the '%s' workload: %s\n",
-			strevsels, argv[0], emsg);
+			sb.buf, argv[0], emsg);
+		strbuf_release(&sb);
 		err = -1;
 		goto out_child;
 	}