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SubjectRe: [PATCH] [RFC] perf: robustify proc and debugfs file recording
Date
In message <29926.1310553581@neuling.org> you wrote:
> Sonny,
>
>
> > 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'm getting a bunch of unused variables warnings when I compile this.
> Care to clean them up?
>
> CC util/trace-event-info.o
> util/trace-event-info.c: In function =E2=80=98read_header_files=E2=80=99:
> util/trace-event-info.c:221:27: error: unused variable =E2=80=98check_size=
> =E2=80=99 [-Werror=3Dunused-variable]
> util/trace-event-info.c:221:21: error: unused variable =E2=80=98size=E2=80=
> =99 [-Werror=3Dunused-variable]
> util/trace-event-info.c: In function =E2=80=98copy_event_system=E2=80=99:
> util/trace-event-info.c:255:27: error: unused variable =E2=80=98check_size=
> =E2=80=99 [-Werror=3Dunused-variable]
> util/trace-event-info.c:255:21: error: unused variable =E2=80=98size=E2=80=
> =99 [-Werror=3Dunused-variable]
> util/trace-event-info.c: In function =E2=80=98read_proc_kallsyms=E2=80=99:
> util/trace-event-info.c:377:21: error: unused variable =E2=80=98check_size=
> =E2=80=99 [-Werror=3Dunused-variable]
> util/trace-event-info.c: In function =E2=80=98read_ftrace_printk=E2=80=99:
> util/trace-event-info.c:394:21: error: unused variable =E2=80=98check_size=
> =E2=80=99 [-Werror=3Dunused-variable]
> cc1: all warnings being treated as errors

Actually, here's an updated patch to fix these..

FYI perf record/annotate/report works fine on my powerpc box here with
this. I don't have modules handy so I've not tested that aspect.

Mikey



From: Sonny Rao <sonnyrao@chromium.org>

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
+++ linux-ozlabs/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, &size, 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, s

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
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 trac

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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