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Subject[PATCH] [RFCv3] perf: robustify proc and debugfs file recording
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In message <1310612277.27864.5.camel@gandalf.stny.rr.com> you wrote:
> On Wed, 2011-07-13 at 17:40 -0700, Sonny Rao wrote:
> > 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.
> >
>
> I get this:
>
> cc1: warnings being treated as errors
> util/trace-event-info.c: In function ‘read_header_files’:
> util/trace-event-info.c:221: error: unused variable ‘size’
> util/trace-event-info.c: In function ‘copy_event_system’:
> util/trace-event-info.c:255: error: unused variable ‘size’
> make: *** [/tmp/build/util/trace-event-info.o] Error 1

Looks like sonny didn't pick up my changes correctly. Here's the
working I tested with the sizep and warnings cleanups.

Mikey



From: Sonny Rao <sonnyrao@chromium.org>

[RFCv3] 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.

Signed-off-by: Sonny Rao <sonnyrao@chromium.org>
Signed-off-by: Michael Neuling <mikey@neuling.org>
---
tools/perf/util/trace-event-info.c | 120 ++++++++-----------------------------
1 file changed, 29 insertions(+), 91 deletions(-)
Index: linux-ozlabs/tools/perf/util/trace-event-info.c
===================================================================
--- linux-ozlabs.orig/tools/perf/util/trace-event-info.c 2011-07-13 20:42:24.442945973 +1000
+++ linux-ozlabs/tools/perf/util/trace-event-info.c 2011-07-14 10:14:19.072946058 +1000
@@ -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;
-
- 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;
+ char buf[BUFSIZ], *sizep;
+ off_t hdr_pos = lseek(output_fd, 0, SEEK_CUR);
+ int r, fd;

fd = open(file, O_RDONLY);
if (fd < 0)
die("Can't read '%s'", file);
- size = copy_file_fd(fd);
- close(fd);

- return size;
-}
-
-static unsigned long get_size_fd(int fd)
-{
- unsigned long long size = 0;
- char buf[BUFSIZ];
- int r;
+ /* put in zeros for file size, then fill true size later */
+ write_or_die(&size, hdr_sz);

do {
r = read(fd, buf, BUFSIZ);
- if (r > 0)
+ if (r > 0) {
size += r;
+ write_or_die(buf, r);
+ }
} while (r > 0);
-
- lseek(fd, 0, SEEK_SET);
-
- return size;
-}
-
-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;
+ /* ugh, handle big-endian hdr_size == 4 */
+ sizep = (char*)&size;
+ if (bigendian())
+ sizep += sizeof(u64) - hdr_sz;
+
+ if (pwrite(output_fd, sizep, hdr_sz, hdr_pos) < 0)
+ die("writing to %s", output_file);
}

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);
}
--
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