--- kernel/trace/ftrace.c

+++ kernel/trace/ftrace.c

@@ -369,11 +369,18 @@ static int function_stat_show(struct seq

{

struct ftrace_profile *rec = v;

char str[KSYM_SYMBOL_LEN];

+ int ret = 0;

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

- static DEFINE_MUTEX(mutex);

static struct trace_seq s;

unsigned long long avg;

#endif

+ mutex_lock(&ftrace_profile_lock);

+

+ /* we raced with function_profile_reset() */

+ if (unlikely(rec->counter == 0)) {

+ ret = -EBUSY;

+ goto out;

+ }

kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);

seq_printf(m, " %-30.30s %10lu", str, rec->counter);

@@ -383,17 +390,17 @@ static int function_stat_show(struct seq

avg = rec->time;

do_div(avg, rec->counter);

- mutex_lock(&mutex);

trace_seq_init(&s);

trace_print_graph_duration(rec->time, &s);

trace_seq_puts(&s, " ");

trace_print_graph_duration(avg, &s);

trace_print_seq(m, &s);

- mutex_unlock(&mutex);

#endif

seq_putc(m, '\n');

+out:

+ mutex_unlock(&ftrace_profile_lock);

- return 0;

+ return ret;

}

static void ftrace_profile_reset(struct ftrace_profile_stat *stat)

@@ -1473,6 +1480,8 @@ static void *t_start(struct seq_file *m,

if (*pos > 0)

return t_hash_start(m, pos);

iter->flags |= FTRACE_ITER_PRINTALL;

+ /* reset in case of seek/pread */

+ iter->flags &= ~FTRACE_ITER_HASH;

return iter;

}

@@ -2393,7 +2402,7 @@ static const struct file_operations ftra

.open = ftrace_filter_open,

.read = seq_read,

.write = ftrace_filter_write,

- .llseek = ftrace_regex_lseek,

+ .llseek = no_llseek,

.release = ftrace_filter_release,

};