perf evlist: Introduce perf_evlist__strerror_tp method

Out of 'perf trace', should be used by other tools that uses
tracepoints.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ramkumar Ramachandra <artagnon@gmail.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-lyvtxhchz4ga8fwht15x8wou@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-trace.c

@@ -1814,27 +1814,11 @@ static int trace__run(struct trace *trace, int argc, const char **argv)
 	trace->live = false;
 	return err;
 out_error_tp:
-	switch(errno) {
-	case ENOENT:
-		fputs("Error:\tUnable to find debugfs\n"
-		      "Hint:\tWas your kernel was compiled with debugfs support?\n"
-		      "Hint:\tIs the debugfs filesystem mounted?\n"
-		      "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'\n",
-		      trace->output);
-		break;
-	case EACCES:
-		fprintf(trace->output,
-			"Error:\tNo permissions to read %s/tracing/events/raw_syscalls\n"
-			"Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
-			debugfs_mountpoint, debugfs_mountpoint);
-		break;
-	default: {
-		char bf[256];
-		fprintf(trace->output, "Can't trace: %s\n",
-			strerror_r(errno, bf, sizeof(bf)));
-	}
-		break;
-	}
+{
+	char errbuf[BUFSIZ];
+	perf_evlist__strerror_tp(evlist, errno, errbuf, sizeof(errbuf));
+	fprintf(trace->output, "%s\n", errbuf);
+}
 	goto out_delete_evlist;
 }
 

tools/perf/util/evlist.c

@@ -1126,3 +1126,30 @@ size_t perf_evlist__fprintf(struct perf_evlist *evlist, FILE *fp)
 
 	return printed + fprintf(fp, "\n");;
 }
+
+int perf_evlist__strerror_tp(struct perf_evlist *evlist __maybe_unused,
+			     int err, char *buf, size_t size)
+{
+	char sbuf[128];
+
+	switch (err) {
+	case ENOENT:
+		scnprintf(buf, size, "%s",
+			  "Error:\tUnable to find debugfs\n"
+			  "Hint:\tWas your kernel was compiled with debugfs support?\n"
+			  "Hint:\tIs the debugfs filesystem mounted?\n"
+			  "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
+		break;
+	case EACCES:
+		scnprintf(buf, size,
+			  "Error:\tNo permissions to read %s/tracing/events/raw_syscalls\n"
+			  "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
+			  debugfs_mountpoint, debugfs_mountpoint);
+		break;
+	default:
+		scnprintf(buf, size, "%s", strerror_r(err, sbuf, sizeof(sbuf)));
+		break;
+	}
+
+	return 0;
+}

tools/perf/util/evlist.h

@@ -168,6 +168,8 @@ static inline struct perf_evsel *perf_evlist__last(struct perf_evlist *evlist)
 
 size_t perf_evlist__fprintf(struct perf_evlist *evlist, FILE *fp);
 
+int perf_evlist__strerror_tp(struct perf_evlist *evlist, int err, char *buf, size_t size);
+
 static inline unsigned int perf_mmap__read_head(struct perf_mmap *mm)
 {
 	struct perf_event_mmap_page *pc = mm->base;