1 files changed, 19 insertions, 8 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ae6fa2d1cdf7..e71a8be4a6ee 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -652,8 +652,6 @@ static struct {
         ARCH_TRACE_CLOCKS
 };
 
-int trace_clock_id;
-
 /*
  * trace_parser_get_init - gets the buffer for trace parser
  */
@@ -843,7 +841,15 @@ __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 
         memcpy(max_data->comm, tsk->comm, TASK_COMM_LEN);
         max_data->pid = tsk->pid;
-        max_data->uid = task_uid(tsk);
+        /*
+         * If tsk == current, then use current_uid(), as that does not use
+         * RCU. The irq tracer can be called out of RCU scope.
+         */
+        if (tsk == current)
+                max_data->uid = current_uid();
+        else
+                max_data->uid = task_uid(tsk);
+
         max_data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
         max_data->policy = tsk->policy;
         max_data->rt_priority = tsk->rt_priority;
@@ -2818,7 +2824,7 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot)
                 iter->iter_flags |= TRACE_FILE_ANNOTATE;
 
         /* Output in nanoseconds only if we are using a clock in nanoseconds. */
-        if (trace_clocks[trace_clock_id].in_ns)
+        if (trace_clocks[tr->clock_id].in_ns)
                 iter->iter_flags |= TRACE_FILE_TIME_IN_NS;
 
         /* stop the trace while dumping if we are not opening "snapshot" */
@@ -3817,7 +3823,7 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
                 iter->iter_flags |= TRACE_FILE_LAT_FMT;
 
         /* Output in nanoseconds only if we are using a clock in nanoseconds. */
-        if (trace_clocks[trace_clock_id].in_ns)
+        if (trace_clocks[tr->clock_id].in_ns)
                 iter->iter_flags |= TRACE_FILE_TIME_IN_NS;
 
         iter->cpu_file = tc->cpu;
@@ -5087,7 +5093,7 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
         cnt = ring_buffer_bytes_cpu(trace_buf->buffer, cpu);
         trace_seq_printf(s, "bytes: %ld\n", cnt);
 
-        if (trace_clocks[trace_clock_id].in_ns) {
+        if (trace_clocks[tr->clock_id].in_ns) {
                 /* local or global for trace_clock */
                 t = ns2usecs(ring_buffer_oldest_event_ts(trace_buf->buffer, cpu));
                 usec_rem = do_div(t, USEC_PER_SEC);
@@ -6216,10 +6222,15 @@ __init static int tracer_alloc_buffers(void)
 
         trace_init_cmdlines();
 
-        register_tracer(&nop_trace);
-
+        /*
+         * register_tracer() might reference current_trace, so it
+         * needs to be set before we register anything. This is
+         * just a bootstrap of current_trace anyway.
+         */
         global_trace.current_trace = &nop_trace;
 
+        register_tracer(&nop_trace);
+
         /* All seems OK, enable tracing */
         tracing_disabled = 0;