ftrace: Allow to remove a single function from function graph filter

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>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 7968762..43bec99 100644 (file)
--- 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 (file)
--- 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++) {