tracing: t_start: reset FTRACE_ITER_HASH in case of seek/pread

[karo-tx-linux.git] / kernel / trace / ftrace.c

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 6d2cb14f9449083c9a2e78f507b9c1255c8e7ca2..6b316b3928a3168b41faa4b02615d05e08f56323 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -381,12 +381,19 @@ static int function_stat_show(struct seq_file *m, void *v)
 {
        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;
        unsigned long long stddev;
 #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);
@@ -408,7 +415,6 @@ static int function_stat_show(struct seq_file *m, void *v)
                do_div(stddev, (rec->counter - 1) * 1000);
        }
 
-       mutex_lock(&mutex);
        trace_seq_init(&s);
        trace_print_graph_duration(rec->time, &s);
        trace_seq_puts(&s, "    ");
@@ -416,11 +422,12 @@ static int function_stat_show(struct seq_file *m, void *v)
        trace_seq_puts(&s, "    ");
        trace_print_graph_duration(stddev, &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)
@@ -1503,6 +1510,8 @@ static void *t_start(struct seq_file *m, loff_t *pos)
                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;
        }
 
@@ -2410,7 +2419,7 @@ static const struct file_operations ftrace_filter_fops = {
        .open = ftrace_filter_open,
        .read = seq_read,
        .write = ftrace_filter_write,
-       .llseek = ftrace_regex_lseek,
+       .llseek = no_llseek,
        .release = ftrace_filter_release,
 };