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Subject[PATCH 2/3] ftrace: Allow to remove a single function from function graph filter
From: Li Zefan <lizf@cn.fujitsu.com>

I don't see why we can only clear all functions from the filter.

After patching:

# echo sys_open > set_graph_function
# echo sys_close >> set_graph_function
# cat set_graph_function
sys_open
sys_close
# echo '!sys_close' >> set_graph_function
# cat set_graph_function
sys_open
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4B726388.2000408@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/ftrace.c | 51 +++++++++++++++++++++++++++++-------------------
kernel/trace/trace.h | 3 +-
2 files changed, 33 insertions(+), 21 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 7968762..43bec99 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2426,6 +2426,7 @@ static const struct file_operations ftrace_notrace_fops = {
static DEFINE_MUTEX(graph_lock);

int ftrace_graph_count;
+int ftrace_graph_filter_enabled;
unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly;

static void *
@@ -2448,7 +2449,7 @@ static void *g_start(struct seq_file *m, loff_t *pos)
mutex_lock(&graph_lock);

/* Nothing, tell g_show to print all functions are enabled */
- if (!ftrace_graph_count && !*pos)
+ if (!ftrace_graph_filter_enabled && !*pos)
return (void *)1;

return __g_next(m, pos);
@@ -2494,6 +2495,7 @@ ftrace_graph_open(struct inode *inode, struct file *file)
mutex_lock(&graph_lock);
if ((file->f_mode & FMODE_WRITE) &&
(file->f_flags & O_TRUNC)) {
+ ftrace_graph_filter_enabled = 0;
ftrace_graph_count = 0;
memset(ftrace_graph_funcs, 0, sizeof(ftrace_graph_funcs));
}
@@ -2519,7 +2521,7 @@ ftrace_set_func(unsigned long *array, int *idx, char *buffer)
struct dyn_ftrace *rec;
struct ftrace_page *pg;
int search_len;
- int found = 0;
+ int fail = 1;
int type, not;
char *search;
bool exists;
@@ -2530,37 +2532,51 @@ ftrace_set_func(unsigned long *array, int *idx, char *buffer)

/* decode regex */
type = filter_parse_regex(buffer, strlen(buffer), &search, &not);
- if (not)
- return -EINVAL;
+ if (!not && *idx >= FTRACE_GRAPH_MAX_FUNCS)
+ return -EBUSY;

search_len = strlen(search);

mutex_lock(&ftrace_lock);
do_for_each_ftrace_rec(pg, rec) {

- if (*idx >= FTRACE_GRAPH_MAX_FUNCS)
- break;
-
if (rec->flags & (FTRACE_FL_FAILED | FTRACE_FL_FREE))
continue;

if (ftrace_match_record(rec, search, search_len, type)) {
- /* ensure it is not already in the array */
+ /* if it is in the array */
exists = false;
- for (i = 0; i < *idx; i++)
+ for (i = 0; i < *idx; i++) {
if (array[i] == rec->ip) {
exists = true;
break;
}
- if (!exists)
- array[(*idx)++] = rec->ip;
- found = 1;
+ }
+
+ if (!not) {
+ fail = 0;
+ if (!exists) {
+ array[(*idx)++] = rec->ip;
+ if (*idx >= FTRACE_GRAPH_MAX_FUNCS)
+ goto out;
+ }
+ } else {
+ if (exists) {
+ array[i] = array[--(*idx)];
+ array[*idx] = 0;
+ fail = 0;
+ }
+ }
}
} while_for_each_ftrace_rec();
-
+out:
mutex_unlock(&ftrace_lock);

- return found ? 0 : -EINVAL;
+ if (fail)
+ return -EINVAL;
+
+ ftrace_graph_filter_enabled = 1;
+ return 0;
}

static ssize_t
@@ -2570,16 +2586,11 @@ ftrace_graph_write(struct file *file, const char __user *ubuf,
struct trace_parser parser;
ssize_t read, ret;

- if (!cnt || cnt < 0)
+ if (!cnt)
return 0;

mutex_lock(&graph_lock);

- if (ftrace_graph_count >= FTRACE_GRAPH_MAX_FUNCS) {
- ret = -EBUSY;
- goto out_unlock;
- }
-
if (trace_parser_get_init(&parser, FTRACE_BUFF_MAX)) {
ret = -ENOMEM;
goto out_unlock;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index ce077fb..b477fce 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -497,6 +497,7 @@ trace_print_graph_duration(unsigned long long duration, struct trace_seq *s);
#ifdef CONFIG_DYNAMIC_FTRACE
/* TODO: make this variable */
#define FTRACE_GRAPH_MAX_FUNCS 32
+extern int ftrace_graph_filter_enabled;
extern int ftrace_graph_count;
extern unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS];

@@ -504,7 +505,7 @@ static inline int ftrace_graph_addr(unsigned long addr)
{
int i;

- if (!ftrace_graph_count)
+ if (!ftrace_graph_filter_enabled)
return 1;

for (i = 0; i < ftrace_graph_count; i++) {
--
1.6.5



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