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Subject[PATCH] tracing: dont reset set_ftrace_filter/notrace when opened with r/w perm
If user setup set_ftrace_filter/set_ftrace_notrace files and then opens them
with read&write permissions, the previous setup will be removed.

Tested with following program:

[snip]
#include <stdio.h>
#include <string.h>

int main(int argc, char **argv)
{
FILE *f;
char *mode = "w+";
char *file = argv[1];
if (argc == 3)
mode = argv[2];
if (NULL == (f = fopen(file, mode))) {
perror("fopen failed");
return -1;
}
while(!feof(f)) {
#define BUFLEN 100
char buf[BUFLEN];
memset(buf, 0, BUFLEN);
fgets(buf, BUFLEN, f);
printf(buf);
}
fclose(f);
return 0;
}
[snip]
wbr,
jirka


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

---
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 4521c77..11394bc 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1661,10 +1661,6 @@ ftrace_regex_open(struct inode *inode, struct file *file, int enable)
return -ENOMEM;

mutex_lock(&ftrace_regex_lock);
- if ((file->f_mode & FMODE_WRITE) &&
- !(file->f_flags & O_APPEND))
- ftrace_filter_reset(enable);
-
if (file->f_mode & FMODE_READ) {
iter->pg = ftrace_pages_start;
iter->flags = enable ? FTRACE_ITER_FILTER :
@@ -2260,6 +2256,9 @@ ftrace_regex_write(struct file *file, const char __user *ubuf,
return 0;

mutex_lock(&ftrace_regex_lock);
+ if ((file->f_mode & FMODE_WRITE) &&
+ !(file->f_flags & O_APPEND))
+ ftrace_filter_reset(enable);

if (file->f_mode & FMODE_READ) {
struct seq_file *m = file->private_data;

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