lkml.org 
[lkml]   [2009]   [Aug]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] tracing: FTRACE_ITER_CONT handling fix
Hi,

if one filter item (for set_ftrace_filter and set_ftrace_notrace) is being
setup by more than 1 consecutive writes (FTRACE_ITER_CONT flag), it won't
be handled corretly.

I used following program to test/verify:

[snip]
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>

int main(int argc, char **argv)
{
int fd, i;
char *file = argv[1];

if (-1 == (fd = open(file, O_WRONLY))) {
perror("open failed");
return -1;
}

for(i = 0; i < (argc - 2); i++) {
int len = strlen(argv[2+i]);
int cnt, off = 0;

while(len) {
cnt = write(fd, argv[2+i] + off, len);
len -= cnt;
off += cnt;
}
}

close(fd);
return 0;
}
[snip]

before change:
sh-4.0# echo > ./set_ftrace_filter
sh-4.0# /test ./set_ftrace_filter "sys" "_open "
sh-4.0# cat ./set_ftrace_filter
#### all functions enabled ####
sh-4.0#

after change:
sh-4.0# echo > ./set_ftrace_notrace
sh-4.0# test ./set_ftrace_notrace "sys" "_open "
sh-4.0# cat ./set_ftrace_notrace
sys_open
sh-4.0#

wbr,
jirka


Signed-off-by: Jiri Olsa <jolsa@redhat.com>

---
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 0948634..da0757a 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2233,7 +2233,11 @@ ftrace_regex_write(struct file *file, const char __user *ubuf,
read++;
cnt--;

- if (!(iter->flags & ~FTRACE_ITER_CONT)) {
+ /*
+ * If the parser haven't finished with the last write,
+ * continue reading the user input without skipping spaces.
+ */
+ if (!(iter->flags & FTRACE_ITER_CONT)) {
/* skip white space */
while (cnt && isspace(ch)) {
ret = get_user(ch, ubuf++);
@@ -2243,8 +2247,9 @@ ftrace_regex_write(struct file *file, const char __user *ubuf,
cnt--;
}

+ /* only spaces were written */
if (isspace(ch)) {
- file->f_pos += read;
+ *ppos += read;
ret = read;
goto out;
}
@@ -2273,12 +2278,12 @@ ftrace_regex_write(struct file *file, const char __user *ubuf,
if (ret)
goto out;
iter->buffer_idx = 0;
- } else
+ } else {
iter->flags |= FTRACE_ITER_CONT;
+ iter->buffer[iter->buffer_idx++] = ch;
+ }

-
- file->f_pos += read;
-
+ *ppos += read;
ret = read;
out:
mutex_unlock(&ftrace_regex_lock);

\
 
 \ /
  Last update: 2009-08-11 17:31    [W:0.063 / U:1.928 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site