ring-buffer: Check if buffer exists before polling

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

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 21920add7972c40562e73efb48535d4b7ba36b84..8fe92ce43f39fc7a85b5c937533e22a089e6a56f 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1027,13 +1027,13 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
 }
 #endif /* CONFIG_TRACER_MAX_TRACE */
 
-static void default_wait_pipe(struct trace_iterator *iter)
+static int default_wait_pipe(struct trace_iterator *iter)
 {
        /* Iterators are static, they should be filled or empty */
        if (trace_buffer_iter(iter, iter->cpu_file))
-               return;
+               return 0;
 
-       ring_buffer_wait(iter->trace_buffer->buffer, iter->cpu_file);
+       return ring_buffer_wait(iter->trace_buffer->buffer, iter->cpu_file);
 }
 
 #ifdef CONFIG_FTRACE_STARTUP_TEST
@@ -4054,17 +4054,19 @@ tracing_poll_pipe(struct file *filp, poll_table *poll_table)
  *
  *     Anyway, this is really very primitive wakeup.
  */
-void poll_wait_pipe(struct trace_iterator *iter)
+int poll_wait_pipe(struct trace_iterator *iter)
 {
        set_current_state(TASK_INTERRUPTIBLE);
        /* sleep for 100 msecs, and try again. */
        schedule_timeout(HZ / 10);
+       return 0;
 }
 
 /* Must be called with trace_types_lock mutex held. */
 static int tracing_wait_pipe(struct file *filp)
 {
        struct trace_iterator *iter = filp->private_data;
+       int ret;
 
        while (trace_empty(iter)) {
 
@@ -4074,10 +4076,13 @@ static int tracing_wait_pipe(struct file *filp)
 
                mutex_unlock(&iter->mutex);
 
-               iter->trace->wait_pipe(iter);
+               ret = iter->trace->wait_pipe(iter);
 
                mutex_lock(&iter->mutex);
 
+               if (ret)
+                       return ret;
+
                if (signal_pending(current))
                        return -EINTR;
 
@@ -5011,8 +5016,12 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
                                goto out_unlock;
                        }
                        mutex_unlock(&trace_types_lock);
-                       iter->trace->wait_pipe(iter);
+                       ret = iter->trace->wait_pipe(iter);
                        mutex_lock(&trace_types_lock);
+                       if (ret) {
+                               size = ret;
+                               goto out_unlock;
+                       }
                        if (signal_pending(current)) {
                                size = -EINTR;
                                goto out_unlock;
@@ -5224,8 +5233,10 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
                        goto out;
                }
                mutex_unlock(&trace_types_lock);
-               iter->trace->wait_pipe(iter);
+               ret = iter->trace->wait_pipe(iter);
                mutex_lock(&trace_types_lock);
+               if (ret)
+                       goto out;
                if (signal_pending(current)) {
                        ret = -EINTR;
                        goto out;