perf evsel: Ensure the fallback message is always written to

JIRA: https://issues.redhat.com/browse/RHEL-78200

upstream
========
commit 24937ee
Author: Ian Rogers <irogers@google.com>
Date: Thu Sep 18 10:24:15 2025 -0700

description
===========
The fallback message is unconditionally printed in places like
record__open().

If no fallback is attempted this can lead to printing uninitialized
data, crashes, etc.

Fixes: c0a5434 ("perf evsel: Introduce event fallback method")
    Signed-off-by: Ian Rogers <irogers@google.com>
    Cc: Adrian Hunter <adrian.hunter@intel.com>
    Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    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: Kan Liang <kan.liang@linux.intel.com>
    Cc: Mark Rutland <mark.rutland@arm.com>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Signed-off-by: Anubhav Shelat <ashelat@redhat.com>

Author: AnubhavS1

tools/perf/util/evsel.c

@@ -3562,15 +3562,15 @@ bool evsel__fallback(struct evsel *evsel, struct target *target, int err,
 
 		/* If event has exclude user then don't exclude kernel. */
 		if (evsel->core.attr.exclude_user)
-			return false;
+			goto no_fallback;
 
 		/* Is there already the separator in the name. */
 		if (strchr(name, '/') ||
 		    (strchr(name, ':') && !evsel->is_libpfm_event))
 			sep = "";
 
 		if (asprintf(&new_name, "%s%su", name, sep) < 0)
-			return false;
+			goto no_fallback;
 
 		free(evsel->name);
 		evsel->name = new_name;
@@ -3593,17 +3593,19 @@ bool evsel__fallback(struct evsel *evsel, struct target *target, int err,
 			sep = "";
 
 		if (asprintf(&new_name, "%s%sH", name, sep) < 0)
-			return false;
+			goto no_fallback;
 
 		free(evsel->name);
 		evsel->name = new_name;
 		/* Apple M1 requires exclude_guest */
-		scnprintf(msg, msgsize, "trying to fall back to excluding guest samples");
+		scnprintf(msg, msgsize, "Trying to fall back to excluding guest samples");
 		evsel->core.attr.exclude_guest = 1;
 
 		return true;
 	}
-
+no_fallback:
+	scnprintf(msg, msgsize, "No fallback found for '%s' for error %d",
+		  evsel__name(evsel), err);
 	return false;
 }