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Subject[tip:perf/core] perf: Robustify proc and debugfs file recording
Commit-ID:  259032bfe379281bf7cba512b7705bdb4ce41db5
Gitweb: http://git.kernel.org/tip/259032bfe379281bf7cba512b7705bdb4ce41db5
Author: Sonny Rao <sonnyrao@chromium.org>
AuthorDate: Thu, 14 Jul 2011 13:34:43 +1000
Committer: Steven Rostedt <rostedt@goodmis.org>
CommitDate: Thu, 14 Jul 2011 15:53:01 -0400

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>
---
tools/perf/util/trace-event-info.c | 120 +++++++++---------------------------
1 files changed, 29 insertions(+), 91 deletions(-)
diff --git a/tools/perf/util/trace-event-info.c b/tools/perf/util/trace-event-info.c
index 35729f4..3403f81 100644
--- a/tools/perf/util/trace-event-info.c
+++ b/tools/perf/util/trace-event-info.c
@@ -183,106 +183,59 @@ int bigendian(void)
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 bool name_in_tp_list(char *sys, struct tracepoint_path *tps)

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 @@ static void copy_event_system(const char *sys, struct tracepoint_path *tps)
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_event_files(struct tracepoint_path *tps)

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 @@ static void read_proc_kallsyms(void)
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 @@ static void read_ftrace_printk(void)
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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