tracing: Separate out trace events from global variables

[firefly-linux-kernel-4.4.55.git] / kernel / trace / trace.c

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c2e2c23103742e3a3e53cf7b318aa0c804f5e1a8..932931897b8d2dd4d3544889e731191f4ba67346 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -189,6 +189,8 @@ unsigned long long ns2usecs(cycle_t nsec)
  */
 static struct trace_array      global_trace;
 
+LIST_HEAD(ftrace_trace_arrays);
+
 static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);
 
 int filter_current_check_discard(struct ring_buffer *buffer,
@@ -704,7 +706,7 @@ __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 void
 update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 {
-       struct ring_buffer *buf = tr->buffer;
+       struct ring_buffer *buf;
 
        if (trace_stop_count)
                return;
@@ -719,6 +721,7 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 
        arch_spin_lock(&ftrace_max_lock);
 
+       buf = tr->buffer;
        tr->buffer = max_tr.buffer;
        max_tr.buffer = buf;
 
@@ -2400,6 +2403,27 @@ static void test_ftrace_alive(struct seq_file *m)
        seq_printf(m, "#          MAY BE MISSING FUNCTION EVENTS\n");
 }
 
+#ifdef CONFIG_TRACER_MAX_TRACE
+static void print_snapshot_help(struct seq_file *m, struct trace_iterator *iter)
+{
+       if (iter->trace->allocated_snapshot)
+               seq_printf(m, "#\n# * Snapshot is allocated *\n#\n");
+       else
+               seq_printf(m, "#\n# * Snapshot is freed *\n#\n");
+
+       seq_printf(m, "# Snapshot commands:\n");
+       seq_printf(m, "# echo 0 > snapshot : Clears and frees snapshot buffer\n");
+       seq_printf(m, "# echo 1 > snapshot : Allocates snapshot buffer, if not already allocated.\n");
+       seq_printf(m, "#                      Takes a snapshot of the main buffer.\n");
+       seq_printf(m, "# echo 2 > snapshot : Clears snapshot buffer (but does not allocate)\n");
+       seq_printf(m, "#                      (Doesn't have to be '2' works with any number that\n");
+       seq_printf(m, "#                       is not a '0' or '1')\n");
+}
+#else
+/* Should never be called */
+static inline void print_snapshot_help(struct seq_file *m, struct trace_iterator *iter) { }
+#endif
+
 static int s_show(struct seq_file *m, void *v)
 {
        struct trace_iterator *iter = v;
@@ -2411,7 +2435,9 @@ static int s_show(struct seq_file *m, void *v)
                        seq_puts(m, "#\n");
                        test_ftrace_alive(m);
                }
-               if (iter->trace && iter->trace->print_header)
+               if (iter->snapshot && trace_empty(iter))
+                       print_snapshot_help(m, iter);
+               else if (iter->trace && iter->trace->print_header)
                        iter->trace->print_header(m);
                else
                        trace_default_header(m);
@@ -2857,11 +2883,25 @@ static int set_tracer_option(struct tracer *trace, char *cmp, int neg)
        return -EINVAL;
 }
 
-static void set_tracer_flags(unsigned int mask, int enabled)
+/* Some tracers require overwrite to stay enabled */
+int trace_keep_overwrite(struct tracer *tracer, u32 mask, int set)
+{
+       if (tracer->enabled && (mask & TRACE_ITER_OVERWRITE) && !set)
+               return -1;
+
+       return 0;
+}
+
+int set_tracer_flag(unsigned int mask, int enabled)
 {
        /* do nothing if flag is already set */
        if (!!(trace_flags & mask) == !!enabled)
-               return;
+               return 0;
+
+       /* Give the tracer a chance to approve the change */
+       if (current_trace->flag_changed)
+               if (current_trace->flag_changed(current_trace, mask, !!enabled))
+                       return -EINVAL;
 
        if (enabled)
                trace_flags |= mask;
@@ -2871,18 +2911,24 @@ static void set_tracer_flags(unsigned int mask, int enabled)
        if (mask == TRACE_ITER_RECORD_CMD)
                trace_event_enable_cmd_record(enabled);
 
-       if (mask == TRACE_ITER_OVERWRITE)
+       if (mask == TRACE_ITER_OVERWRITE) {
                ring_buffer_change_overwrite(global_trace.buffer, enabled);
+#ifdef CONFIG_TRACER_MAX_TRACE
+               ring_buffer_change_overwrite(max_tr.buffer, enabled);
+#endif
+       }
 
        if (mask == TRACE_ITER_PRINTK)
                trace_printk_start_stop_comm(enabled);
+
+       return 0;
 }
 
 static int trace_set_options(char *option)
 {
        char *cmp;
        int neg = 0;
-       int ret = 0;
+       int ret = -ENODEV;
        int i;
 
        cmp = strstrip(option);
@@ -2892,19 +2938,20 @@ static int trace_set_options(char *option)
                cmp += 2;
        }
 
+       mutex_lock(&trace_types_lock);
+
        for (i = 0; trace_options[i]; i++) {
                if (strcmp(cmp, trace_options[i]) == 0) {
-                       set_tracer_flags(1 << i, !neg);
+                       ret = set_tracer_flag(1 << i, !neg);
                        break;
                }
        }
 
        /* If no option could be set, test the specific tracer options */
-       if (!trace_options[i]) {
-               mutex_lock(&trace_types_lock);
+       if (!trace_options[i])
                ret = set_tracer_option(current_trace, cmp, neg);
-               mutex_unlock(&trace_types_lock);
-       }
+
+       mutex_unlock(&trace_types_lock);
 
        return ret;
 }
@@ -2914,6 +2961,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
                        size_t cnt, loff_t *ppos)
 {
        char buf[64];
+       int ret;
 
        if (cnt >= sizeof(buf))
                return -EINVAL;
@@ -2923,7 +2971,9 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
 
        buf[cnt] = 0;
 
-       trace_set_options(buf);
+       ret = trace_set_options(buf);
+       if (ret < 0)
+               return ret;
 
        *ppos += cnt;
 
@@ -3227,6 +3277,9 @@ static int tracing_set_tracer(const char *buf)
                goto out;
 
        trace_branch_disable();
+
+       current_trace->enabled = false;
+
        if (current_trace->reset)
                current_trace->reset(tr);
 
@@ -3271,6 +3324,7 @@ static int tracing_set_tracer(const char *buf)
        }
 
        current_trace = t;
+       current_trace->enabled = true;
        trace_branch_enable(tr);
  out:
        mutex_unlock(&trace_types_lock);
@@ -4144,8 +4198,6 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt,
        default:
                if (current_trace->allocated_snapshot)
                        tracing_reset_online_cpus(&max_tr);
-               else
-                       ret = -EINVAL;
                break;
        }
 
@@ -4759,7 +4811,13 @@ trace_options_core_write(struct file *filp, const char __user *ubuf, size_t cnt,
 
        if (val != 0 && val != 1)
                return -EINVAL;
-       set_tracer_flags(1 << index, val);
+
+       mutex_lock(&trace_types_lock);
+       ret = set_tracer_flag(1 << index, val);
+       mutex_unlock(&trace_types_lock);
+
+       if (ret < 0)
+               return ret;
 
        *ppos += cnt;
 
@@ -5303,6 +5361,12 @@ __init static int tracer_alloc_buffers(void)
 
        register_die_notifier(&trace_die_notifier);
 
+       global_trace.flags = TRACE_ARRAY_FL_GLOBAL;
+
+       INIT_LIST_HEAD(&global_trace.systems);
+       INIT_LIST_HEAD(&global_trace.events);
+       list_add(&global_trace.list, &ftrace_trace_arrays);
+
        while (trace_boot_options) {
                char *option;