tracing: handle broken names in ftrace filter

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#

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
LKML-Reference: <20090811152904.GA26065@jolsa.lab.eng.brq.redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 1e1d23c263086635ec225dd762aa47d880002b35..25edd5cc5935cae5d76342cf04e2bed40c22f00d 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2278,7 +2278,11 @@ 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++);
@@ -2288,8 +2292,9 @@ 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;
                }
@@ -2319,12 +2324,12 @@ 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);