perf: Robustify proc and debugfs file recording

While attempting to create a timechart of boot up I found perf didn't tolerate modules being loaded/unloaded. This patch fixes this by reading the file once and then writing the size read at the correct point in the file. It also simplifies the code somewhat. Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Signed-off-by: Sonny Rao <sonnyrao@chromium.org> Signed-off-by: Michael Neuling <mikey@neuling.org> Link: http://lkml.kernel.org/r/10011.1310614483@neuling.org Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

perf: Robustify proc and debugfs file recording
While attempting to create a timechart of boot up I found perf didn't tolerate modules being loaded/unloaded. This patch fixes this by reading the file once and then writing the size read at the correct point in the file. It also simplifies the code somewhat. Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Signed-off-by: Sonny Rao <sonnyrao@chromium.org> Signed-off-by: Michael Neuling <mikey@neuling.org> Link: http://lkml.kernel.org/r/10011.1310614483@neuling.org Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Sonny Rao · Steven Rostedt
1 parent 6331c28c96
Showing 1 changed file with 29 additions and 91 deletions Side-by-side Diff
tools/perf/util/trace-event-info.c
@@ -183,106 +183,59 @@
 	return *ptr == 0x01020304;
 }
  
-static unsigned long long copy_file_fd(int fd)
+/* unfortunately, you can not stat debugfs or proc files for size */
+static void record_file(const char *file, size_t hdr_sz)
 {
 	unsigned long long size = 0;
-	char buf[BUFSIZ];
-	int r;
+	char buf[BUFSIZ], *sizep;
+	off_t hdr_pos = lseek(output_fd, 0, SEEK_CUR);
+	int r, fd;
  
-	do {
-		r = read(fd, buf, BUFSIZ);
-		if (r > 0) {
-			size += r;
-			write_or_die(buf, r);
-		}
-	} while (r > 0);
-
-	return size;
-}
-
-static unsigned long long copy_file(const char *file)
-{
-	unsigned long long size = 0;
-	int fd;
-
 	fd = open(file, O_RDONLY);
 	if (fd < 0)
 		die("Can't read '%s'", file);
-	size = copy_file_fd(fd);
-	close(fd);
  
-	return size;
-}
+	/* put in zeros for file size, then fill true size later */
+	write_or_die(&size, hdr_sz);
  
-static unsigned long get_size_fd(int fd)
-{
-	unsigned long long size = 0;
-	char buf[BUFSIZ];
-	int r;
-
 	do {
 		r = read(fd, buf, BUFSIZ);
-		if (r > 0)
+		if (r > 0) {
 			size += r;
+			write_or_die(buf, r);
+		}
 	} while (r > 0);
+	close(fd);
  
-	lseek(fd, 0, SEEK_SET);
+	/* ugh, handle big-endian hdr_size == 4 */
+	sizep = (char*)&size;
+	if (bigendian())
+		sizep += sizeof(u64) - hdr_sz;
  
-	return size;
+	if (pwrite(output_fd, sizep, hdr_sz, hdr_pos) < 0)
+		die("writing to %s", output_file);
 }
  
-static unsigned long get_size(const char *file)
-{
-	unsigned long long size = 0;
-	int fd;
-
-	fd = open(file, O_RDONLY);
-	if (fd < 0)
-		die("Can't read '%s'", file);
-	size = get_size_fd(fd);
-	close(fd);
-
-	return size;
-}
-
 static void read_header_files(void)
 {
-	unsigned long long size, check_size;
 	char *path;
-	int fd;
+	struct stat st;
  
 	path = get_tracing_file("events/header_page");
-	fd = open(path, O_RDONLY);
-	if (fd < 0)
+	if (stat(path, &st) < 0)
 		die("can't read '%s'", path);
  
-	/* unfortunately, you can not stat debugfs files for size */
-	size = get_size_fd(fd);
-
 	write_or_die("header_page", 12);
-	write_or_die(&size, 8);
-	check_size = copy_file_fd(fd);
-	close(fd);
-
-	if (size != check_size)
-		die("wrong size for '%s' size=%lld read=%lld",
-		    path, size, check_size);
+	record_file(path, 8);
 	put_tracing_file(path);
  
 	path = get_tracing_file("events/header_event");
-	fd = open(path, O_RDONLY);
-	if (fd < 0)
+	if (stat(path, &st) < 0)
 		die("can't read '%s'", path);
  
-	size = get_size_fd(fd);
-
 	write_or_die("header_event", 13);
-	write_or_die(&size, 8);
-	check_size = copy_file_fd(fd);
-	if (size != check_size)
-		die("wrong size for '%s'", path);
+	record_file(path, 8);
 	put_tracing_file(path);
-	close(fd);
 }
  
 static bool name_in_tp_list(char *sys, struct tracepoint_path *tps)
@@ -298,7 +251,6 @@
  
 static void copy_event_system(const char *sys, struct tracepoint_path *tps)
 {
-	unsigned long long size, check_size;
 	struct dirent *dent;
 	struct stat st;
 	char *format;
@@ -338,14 +290,8 @@
 		sprintf(format, "%s/%s/format", sys, dent->d_name);
 		ret = stat(format, &st);
  
-		if (ret >= 0) {
-			/* unfortunately, you can not stat debugfs files for size */
-			size = get_size(format);
-			write_or_die(&size, 8);
-			check_size = copy_file(format);
-			if (size != check_size)
-				die("error in size of file '%s'", format);
-		}
+		if (ret >= 0)
+			record_file(format, 8);
  
 		free(format);
 	}
@@ -426,7 +372,7 @@
  
 static void read_proc_kallsyms(void)
 {
-	unsigned int size, check_size;
+	unsigned int size;
 	const char *path = "/proc/kallsyms";
 	struct stat st;
 	int ret;
  
@@ -438,17 +384,12 @@
 		write_or_die(&size, 4);
 		return;
 	}
-	size = get_size(path);
-	write_or_die(&size, 4);
-	check_size = copy_file(path);
-	if (size != check_size)
-		die("error in size of file '%s'", path);
-
+	record_file(path, 4);
 }
  
 static void read_ftrace_printk(void)
 {
-	unsigned int size, check_size;
+	unsigned int size;
 	char *path;
 	struct stat st;
 	int ret;
@@ -461,11 +402,8 @@
 		write_or_die(&size, 4);
 		goto out;
 	}
-	size = get_size(path);
-	write_or_die(&size, 4);
-	check_size = copy_file(path);
-	if (size != check_size)
-		die("error in size of file '%s'", path);
+	record_file(path, 4);
+
 out:
 	put_tracing_file(path);
 }
...	...	@@ -183,106 +183,59 @@
183	183	return *ptr == 0x01020304;
184	184	}
185	185
186		-static unsigned long long copy_file_fd(int fd)
	186	+/* unfortunately, you can not stat debugfs or proc files for size */
	187	+static void record_file(const char *file, size_t hdr_sz)
187	188	{
188	189	unsigned long long size = 0;
189		- char buf[BUFSIZ];
190		- int r;
	190	+ char buf[BUFSIZ], *sizep;
	191	+ off_t hdr_pos = lseek(output_fd, 0, SEEK_CUR);
	192	+ int r, fd;
191	193
192		- do {
193		- r = read(fd, buf, BUFSIZ);
194		- if (r > 0) {
195		- size += r;
196		- write_or_die(buf, r);
197		- }
198		- } while (r > 0);
199		-
200		- return size;
201		-}
202		-
203		-static unsigned long long copy_file(const char *file)
204		-{
205		- unsigned long long size = 0;
206		- int fd;
207		-
208	194	fd = open(file, O_RDONLY);
209	195	if (fd < 0)
210	196	die("Can't read '%s'", file);
211		- size = copy_file_fd(fd);
212		- close(fd);
213	197
214		- return size;
215		-}
	198	+ /* put in zeros for file size, then fill true size later */
	199	+ write_or_die(&size, hdr_sz);
216	200
217		-static unsigned long get_size_fd(int fd)
218		-{
219		- unsigned long long size = 0;
220		- char buf[BUFSIZ];
221		- int r;
222		-
223	201	do {
224	202	r = read(fd, buf, BUFSIZ);
225		- if (r > 0)
	203	+ if (r > 0) {
226	204	size += r;
	205	+ write_or_die(buf, r);
	206	+ }
227	207	} while (r > 0);
	208	+ close(fd);
228	209
229		- lseek(fd, 0, SEEK_SET);
	210	+ /* ugh, handle big-endian hdr_size == 4 */
	211	+ sizep = (char*)&size;
	212	+ if (bigendian())
	213	+ sizep += sizeof(u64) - hdr_sz;
230	214
231		- return size;
	215	+ if (pwrite(output_fd, sizep, hdr_sz, hdr_pos) < 0)
	216	+ die("writing to %s", output_file);
232	217	}
233	218
234		-static unsigned long get_size(const char *file)
235		-{
236		- unsigned long long size = 0;
237		- int fd;
238		-
239		- fd = open(file, O_RDONLY);
240		- if (fd < 0)
241		- die("Can't read '%s'", file);
242		- size = get_size_fd(fd);
243		- close(fd);
244		-
245		- return size;
246		-}
247		-
248	219	static void read_header_files(void)
249	220	{
250		- unsigned long long size, check_size;
251	221	char *path;
252		- int fd;
	222	+ struct stat st;
253	223
254	224	path = get_tracing_file("events/header_page");
255		- fd = open(path, O_RDONLY);
256		- if (fd < 0)
	225	+ if (stat(path, &st) < 0)
257	226	die("can't read '%s'", path);
258	227
259		- /* unfortunately, you can not stat debugfs files for size */
260		- size = get_size_fd(fd);
261		-
262	228	write_or_die("header_page", 12);
263		- write_or_die(&size, 8);
264		- check_size = copy_file_fd(fd);
265		- close(fd);
266		-
267		- if (size != check_size)
268		- die("wrong size for '%s' size=%lld read=%lld",
269		- path, size, check_size);
	229	+ record_file(path, 8);
270	230	put_tracing_file(path);
271	231
272	232	path = get_tracing_file("events/header_event");
273		- fd = open(path, O_RDONLY);
274		- if (fd < 0)
	233	+ if (stat(path, &st) < 0)
275	234	die("can't read '%s'", path);
276	235
277		- size = get_size_fd(fd);
278		-
279	236	write_or_die("header_event", 13);
280		- write_or_die(&size, 8);
281		- check_size = copy_file_fd(fd);
282		- if (size != check_size)
283		- die("wrong size for '%s'", path);
	237	+ record_file(path, 8);
284	238	put_tracing_file(path);
285		- close(fd);
286	239	}
287	240
288	241	static bool name_in_tp_list(char sys, struct tracepoint_path tps)
...	...	@@ -298,7 +251,6 @@
298	251
299	252	static void copy_event_system(const char sys, struct tracepoint_path tps)
300	253	{
301		- unsigned long long size, check_size;
302	254	struct dirent *dent;
303	255	struct stat st;
304	256	char *format;
...	...	@@ -338,14 +290,8 @@
338	290	sprintf(format, "%s/%s/format", sys, dent->d_name);
339	291	ret = stat(format, &st);
340	292
341		- if (ret >= 0) {
342		- /* unfortunately, you can not stat debugfs files for size */
343		- size = get_size(format);
344		- write_or_die(&size, 8);
345		- check_size = copy_file(format);
346		- if (size != check_size)
347		- die("error in size of file '%s'", format);
348		- }
	293	+ if (ret >= 0)
	294	+ record_file(format, 8);
349	295
350	296	free(format);
351	297	}
...	...	@@ -426,7 +372,7 @@
426	372
427	373	static void read_proc_kallsyms(void)
428	374	{
429		- unsigned int size, check_size;
	375	+ unsigned int size;
430	376	const char *path = "/proc/kallsyms";
431	377	struct stat st;
432	378	int ret;
433	379
...	...	@@ -438,17 +384,12 @@
438	384	write_or_die(&size, 4);
439	385	return;
440	386	}
441		- size = get_size(path);
442		- write_or_die(&size, 4);
443		- check_size = copy_file(path);
444		- if (size != check_size)
445		- die("error in size of file '%s'", path);
446		-
	387	+ record_file(path, 4);
447	388	}
448	389
449	390	static void read_ftrace_printk(void)
450	391	{
451		- unsigned int size, check_size;
	392	+ unsigned int size;
452	393	char *path;
453	394	struct stat st;
454	395	int ret;
...	...	@@ -461,11 +402,8 @@
461	402	write_or_die(&size, 4);
462	403	goto out;
463	404	}
464		- size = get_size(path);
465		- write_or_die(&size, 4);
466		- check_size = copy_file(path);
467		- if (size != check_size)
468		- die("error in size of file '%s'", path);
	405	+ record_file(path, 4);
	406	+
469	407	out:
470	408	put_tracing_file(path);
471	409	}