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SubjectRe: [PATCH] tracing: FTRACE_ITER_CONT handling fix
On Tue, Aug 18, 2009 at 09:01:08PM -0400, Steven Rostedt wrote:
>
> On Tue, 11 Aug 2009, Jiri Olsa wrote:
>
> > 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]
>
> BTW, you did not need to make such a test, just doing:
>
> # echo sys_open | dd of=set_ftrace_filter bs=2
>
> works as well.
>

cool :) thanks

jirka

>
> >
> > 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>
>
> Thanks, applied!
>
> -- Steve
>
> >
> > ---
> > 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);
> >


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