perf symbols: Do not read symbols/data from device files

With mem sampling we could get data source within mapped device file.
Processing such sample would block during report phase on trying to read
the device file.

Chacking for device files and skip the processing if it's detected.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1453290995-18485-2-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/dso.c

@@ -52,6 +52,11 @@ int dso__read_binary_type_filename(const struct dso *dso,
 			debuglink--;
 		if (*debuglink == '/')
 			debuglink++;
+
+		ret = -1;
+		if (!is_regular_file(filename))
+			break;
+
 		ret = filename__read_debuglink(filename, debuglink,
 					       size - (debuglink - filename));
 		}

tools/perf/util/symbol.c

@@ -1466,7 +1466,8 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
 	 * Read the build id if possible. This is required for
 	 * DSO_BINARY_TYPE__BUILDID_DEBUGINFO to work
 	 */
-	if (filename__read_build_id(dso->long_name, build_id, BUILD_ID_SIZE) > 0)
+	if (is_regular_file(name) &&
+	    filename__read_build_id(dso->long_name, build_id, BUILD_ID_SIZE) > 0)
 		dso__set_build_id(dso, build_id);
 
 	/*
@@ -1487,6 +1488,9 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
 						   root_dir, name, PATH_MAX))
 			continue;
 
+		if (!is_regular_file(name))
+			continue;
+
 		/* Name is now the name of the next image to try */
 		if (symsrc__init(ss, dso, name, symtab_type) < 0)
 			continue;

tools/perf/util/util.c

@@ -691,3 +691,13 @@ out:
 
 	return tip;
 }
+
+bool is_regular_file(const char *file)
+{
+	struct stat st;
+
+	if (stat(file, &st))
+		return false;
+
+	return S_ISREG(st.st_mode);
+}

tools/perf/util/util.h

@@ -343,5 +343,6 @@ int fetch_kernel_version(unsigned int *puint,
 #define KVER_PARAM(x)	KVER_VERSION(x), KVER_PATCHLEVEL(x), KVER_SUBLEVEL(x)
 
 const char *perf_tip(const char *dirpath);
+bool is_regular_file(const char *file);
 
 #endif /* GIT_COMPAT_UTIL_H */