tools lib fs: Adopt debugfs open strerrno method

As this is not specific to an evlist and may be used with other tools.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-a9up9mivx1pzdf5tqrqsx62d@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

 	tools/perf/util/include/asm/hash.h

tools/lib/api/fs/debugfs.c

@@ -1,3 +1,4 @@
+#define _GNU_SOURCE
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -98,3 +99,29 @@ char *debugfs_mount(const char *mountpoint)
 out:
 	return debugfs_mountpoint;
 }
+
+int debugfs__strerror_open(int err, char *buf, size_t size)
+{
+	char sbuf[128];
+
+	switch (err) {
+	case ENOENT:
+		snprintf(buf, size, "%s",
+			 "Error:\tUnable to find debugfs\n"
+			 "Hint:\tWas your kernel 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:
+		snprintf(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:
+		snprintf(buf, size, "%s", strerror_r(err, sbuf, sizeof(sbuf)));
+		break;
+	}
+
+	return 0;
+}

tools/lib/api/fs/debugfs.h

@@ -26,4 +26,6 @@ char *debugfs_mount(const char *mountpoint);
 
 extern char debugfs_mountpoint[];
 
+int debugfs__strerror_open(int err, char *buf, size_t size);
+
 #endif /* __API_DEBUGFS_H__ */

tools/perf/builtin-trace.c

@@ -2062,8 +2062,15 @@ static int trace__run(struct trace *trace, int argc, const char **argv)
 		perf_evlist__add_vfs_getname(evlist);
 
 	if ((trace->trace_pgfaults & TRACE_PFMAJ) &&
-	    perf_evlist__add_pgfault(evlist, PERF_COUNT_SW_PAGE_FAULTS_MAJ))
+	    perf_evlist__add_pgfault(evlist, PERF_COUNT_SW_PAGE_FAULTS_MAJ)) {
+		/*
+		 * FIXME: This one needs better error handling, as by now we
+		 * already checked that debugfs is mounted and that we have access to it,
+		 * so probably the case is that something is busted wrt this specific
+		 * software event, ditto for the next gotos to out_error_tp...
+		 */
 		goto out_error_tp;
+	}
 
 	if ((trace->trace_pgfaults & TRACE_PFMIN) &&
 	    perf_evlist__add_pgfault(evlist, PERF_COUNT_SW_PAGE_FAULTS_MIN))
@@ -2203,7 +2210,7 @@ static int trace__run(struct trace *trace, int argc, const char **argv)
 	char errbuf[BUFSIZ];
 
 out_error_tp:
-	perf_evlist__strerror_tp(evlist, errno, errbuf, sizeof(errbuf));
+	debugfs__strerror_open(errno, errbuf, sizeof(errbuf));
 	goto out_error;
 
 out_error_mmap:

tools/perf/util/evlist.c

@@ -1436,33 +1436,6 @@ 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 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;
-}
-
 int perf_evlist__strerror_open(struct perf_evlist *evlist __maybe_unused,
 			       int err, char *buf, size_t size)
 {

tools/perf/util/evlist.h

@@ -183,7 +183,6 @@ 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);
 int perf_evlist__strerror_open(struct perf_evlist *evlist, int err, char *buf, size_t size);
 int perf_evlist__strerror_mmap(struct perf_evlist *evlist, int err, char *buf, size_t size);